Index: django/views/debug.py
===================================================================
--- django/views/debug.py	(revision 16772)
+++ django/views/debug.py	(working copy)
@@ -141,7 +141,7 @@
                 else:
                     # Cleanse only the specified parameters.
                     for param in sensitive_post_parameters:
-                        if param in cleansed:
+                        if cleansed.has_key(param):
                             cleansed[param] = CLEANSED_SUBSTITUTE
                     return cleansed
             else:
@@ -223,8 +223,7 @@
                     'loader': loader_name,
                     'templates': template_list,
                 })
-        if (settings.TEMPLATE_DEBUG and hasattr(self.exc_value, 'source') and
-            isinstance(self.exc_value, TemplateSyntaxError)):
+        if (settings.TEMPLATE_DEBUG and hasattr(self.exc_value, 'django_template_source')):
             self.get_template_exception_info()
 
         frames = self.get_traceback_frames()
@@ -268,7 +267,7 @@
         return t.render(c)
 
     def get_template_exception_info(self):
-        origin, (start, end) = self.exc_value.source
+        origin, (start, end) = self.exc_value.django_template_source
         template_source = origin.reload()
         context_lines = 10
         line = 0
@@ -626,7 +625,7 @@
 {% endif %}
 {% if template_info %}
 <div id="template">
-   <h2>Template error</h2>
+   <h2>Error occured during template rendering</h2>
    <p>In template <code>{{ template_info.name }}</code>, error at line <strong>{{ template_info.line }}</strong></p>
    <h3>{{ template_info.message }}</h3>
    <table class="source{% if template_info.top %} cut-top{% endif %}{% ifnotequal template_info.bottom template_info.total %} cut-bottom{% endifnotequal %}">
Index: django/template/debug.py
===================================================================
--- django/template/debug.py	(revision 16772)
+++ django/template/debug.py	(working copy)
@@ -4,6 +4,7 @@
 from django.utils.safestring import SafeData, EscapeData
 from django.utils.formats import localize
 
+
 class DebugLexer(Lexer):
     def __init__(self, template_string, origin):
         super(DebugLexer, self).__init__(template_string, origin)
@@ -42,9 +43,9 @@
     def error(self, token, msg):
         return self.source_error(token.source, msg)
 
-    def source_error(self, source,msg):
+    def source_error(self, source, msg):
         e = TemplateSyntaxError(msg)
-        e.source = source
+        e.source_template_node = source #Identify the template node that was being rendered when the error occurred.
         return e
 
     def create_nodelist(self):
@@ -67,21 +68,17 @@
             e.source = token.source
 
 class DebugNodeList(NodeList):
+    '''
+    A list of nodes that is instantiated when debug is True - this is the nerve center of exceptions that occur during template rendering. 
+    '''
     def render_node(self, node, context):
-        try:
-            result = node.render(context)
-        except TemplateSyntaxError, e:
-            if not hasattr(e, 'source'):
-                e.source = node.source
-            raise
+        try:           
+            return node.render(context) 
         except Exception, e:
-            from sys import exc_info
-            wrapped = TemplateSyntaxError(u'Caught %s while rendering: %s' %
-                (e.__class__.__name__, force_unicode(e, errors='replace')))
-            wrapped.source = getattr(e, 'template_node_source', node.source)
-            wrapped.exc_info = exc_info()
-            raise wrapped, None, wrapped.exc_info[2]
-        return result
+            if not hasattr(e, 'source_template_node'): #Have we already identified the node where the problem occured?
+                e.django_template_source = node.source #...if not, let's annotate the exception with that - the template will use this to show information about the template just before the traceback on the exception page.
+            raise e
+        
 
 class DebugVariableNode(VariableNode):
     def render(self, context):
Index: tests/regressiontests/templates/tests.py
===================================================================
--- tests/regressiontests/templates/tests.py	(revision 16772)
+++ tests/regressiontests/templates/tests.py	(working copy)
@@ -1,5 +1,6 @@
 # -*- coding: utf-8 -*-
 from django.conf import settings
+from django.core.urlresolvers import NoReverseMatch
 
 if __name__ == '__main__':
     # When running this file in isolation, we need to set up the configuration
@@ -20,7 +21,7 @@
 from django.template import loader
 from django.template.loaders import app_directories, filesystem, cached
 from django.test.utils import (get_warnings_state, restore_warnings_state,
-    setup_test_template_loader, restore_template_loaders)
+    setup_test_template_loader, restore_template_loaders, override_settings)
 from django.utils import unittest
 from django.utils.formats import date_format
 from django.utils.translation import activate, deactivate, ugettext as _
@@ -309,9 +310,9 @@
             r = None
             try:
                 r = tmpl.render(template.Context({}))
-            except template.TemplateSyntaxError, e:
+            except template.TemplateDoesNotExist, e:
                 settings.TEMPLATE_DEBUG = old_td
-                self.assertEqual(e.args[0], 'Caught TemplateDoesNotExist while rendering: missing.html')
+                self.assertEqual(e.args[0], 'missing.html')
             self.assertEqual(r, None, 'Template rendering unexpectedly succeeded, produced: ->%r<-' % r)
         finally:
             loader.template_source_loaders = old_loaders
@@ -336,8 +337,8 @@
             r = None
             try:
                 r = tmpl.render(template.Context({}))
-            except template.TemplateSyntaxError, e:
-                self.assertEqual(e.args[0], 'Caught TemplateDoesNotExist while rendering: missing.html')
+            except template.TemplateDoesNotExist, e:
+                self.assertEqual(e.args[0], 'missing.html')
             self.assertEqual(r, None, 'Template rendering unexpectedly succeeded, produced: ->%r<-' % r)
 
             # For the cached loader, repeat the test, to ensure the first attempt did not cache a
@@ -345,8 +346,8 @@
             tmpl = loader.get_template(load_name)
             try:
                 tmpl.render(template.Context({}))
-            except template.TemplateSyntaxError, e:
-                self.assertEqual(e.args[0], 'Caught TemplateDoesNotExist while rendering: missing.html')
+            except template.TemplateDoesNotExist, e:
+                self.assertEqual(e.args[0], 'missing.html')
             self.assertEqual(r, None, 'Template rendering unexpectedly succeeded, produced: ->%r<-' % r)
         finally:
             loader.template_source_loaders = old_loaders
@@ -370,15 +371,26 @@
 
         t = Template('{% url will_not_match %}')
         c = Context()
-        try:
-            rendered = t.render(c)
-        except TemplateSyntaxError, e:
-            # Assert that we are getting the template syntax error and not the
-            # string encoding error.
-            self.assertEqual(e.args[0], "Caught NoReverseMatch while rendering: Reverse for 'will_not_match' with arguments '()' and keyword arguments '{}' not found.")
+        self.assertRaises(NoReverseMatch, t.render, c)
 
         settings.SETTINGS_MODULE = old_settings_module
         settings.TEMPLATE_DEBUG = old_template_debug
+        
+    @override_settings(DEBUG=True, TEMPLATE_DEBUG = True)
+    def test_no_wrapped_exception(self):
+        """
+        Previously exceptions were wrapped by TemplateSyntaxError.  See #16770
+        """
+        from django.template import Template, TemplateSyntaxError
+        c = Context({'coconuts': lambda: 42 / 0})
+        t = Template("{{coconuts}}")        
+        self.assertRaises(ZeroDivisionError, t.render, c) #Dividing by zero ought to cause ZeroDivisionError; we'll instead get TemplateSyntaxError here iff it's been wrapped.
+        
+        #Let's also confirm that the exception has the attribute we need to show the template information on the exception page.
+        try:
+            t.render(c)
+        except ZeroDivisionError, e:
+            self.assertTrue(hasattr(e, 'django_template_source'))
 
     def test_invalid_block_suggestion(self):
         # See #7876
@@ -666,7 +678,7 @@
 
             # In methods that raise an exception without a
             # "silent_variable_attribute" set to True, the exception propagates
-            'filter-syntax14': (r'1{{ var.method4 }}2', {"var": SomeClass()}, (SomeOtherException, SomeOtherException, template.TemplateSyntaxError)),
+            'filter-syntax14': (r'1{{ var.method4 }}2', {"var": SomeClass()}, (SomeOtherException, SomeOtherException)),
 
             # Escaped backslash in argument
             'filter-syntax15': (r'{{ var|default_if_none:"foo\bar" }}', {"var": None}, r'foo\bar'),
@@ -695,8 +707,8 @@
             # In attribute and dict lookups that raise an unexpected exception
             # without a "silent_variable_attribute" set to True, the exception
             # propagates
-            'filter-syntax23': (r'1{{ var.noisy_fail_key }}2', {"var": SomeClass()}, (SomeOtherException, SomeOtherException, template.TemplateSyntaxError)),
-            'filter-syntax24': (r'1{{ var.noisy_fail_attribute }}2', {"var": SomeClass()}, (SomeOtherException, SomeOtherException, template.TemplateSyntaxError)),
+            'filter-syntax23': (r'1{{ var.noisy_fail_key }}2', {"var": SomeClass()}, (SomeOtherException, SomeOtherException)),
+            'filter-syntax24': (r'1{{ var.noisy_fail_attribute }}2', {"var": SomeClass()}, (SomeOtherException, SomeOtherException)),
 
             ### COMMENT SYNTAX ########################################################
             'comment-syntax01': ("{# this is hidden #}hello", {}, "hello"),
@@ -753,7 +765,7 @@
             ### EXCEPTIONS ############################################################
 
             # Raise exception for invalid template name
-            'exception01': ("{% extends 'nonexistent' %}", {}, (template.TemplateDoesNotExist, template.TemplateDoesNotExist, template.TemplateSyntaxError)),
+            'exception01': ("{% extends 'nonexistent' %}", {}, (template.TemplateDoesNotExist, template.TemplateDoesNotExist)),
 
             # Raise exception for invalid template name (in variable)
             'exception02': ("{% extends nonexistent %}", {}, (template.TemplateSyntaxError, template.TemplateDoesNotExist)),
@@ -1050,7 +1062,7 @@
             'include-fail2': ('{% load broken_tag %}', {}, template.TemplateSyntaxError),
             'include-error07': ('{% include "include-fail1" %}', {}, ('', '', RuntimeError)),
             'include-error08': ('{% include "include-fail2" %}', {}, ('', '', template.TemplateSyntaxError)),
-            'include-error09': ('{% include failed_include %}', {'failed_include': 'include-fail1'}, ('', '', template.TemplateSyntaxError)),
+            'include-error09': ('{% include failed_include %}', {'failed_include': 'include-fail1'}, ('', '', RuntimeError)),
             'include-error10': ('{% include failed_include %}', {'failed_include': 'include-fail2'}, ('', '', template.TemplateSyntaxError)),
 
 
@@ -1481,8 +1493,8 @@
 
             # Failures
             'old-url-fail01': ('{% url %}', {}, template.TemplateSyntaxError),
-            'old-url-fail02': ('{% url no_such_view %}', {}, (urlresolvers.NoReverseMatch, urlresolvers.NoReverseMatch, template.TemplateSyntaxError)),
-            'old-url-fail03': ('{% url regressiontests.templates.views.client %}', {}, (urlresolvers.NoReverseMatch, urlresolvers.NoReverseMatch, template.TemplateSyntaxError)),
+            'old-url-fail02': ('{% url no_such_view %}', {}, (urlresolvers.NoReverseMatch, urlresolvers.NoReverseMatch)),
+            'old-url-fail03': ('{% url regressiontests.templates.views.client %}', {}, (urlresolvers.NoReverseMatch, urlresolvers.NoReverseMatch)),
             'old-url-fail04': ('{% url view id, %}', {}, template.TemplateSyntaxError),
             'old-url-fail05': ('{% url view id= %}', {}, template.TemplateSyntaxError),
             'old-url-fail06': ('{% url view a.id=id %}', {}, template.TemplateSyntaxError),
@@ -1522,8 +1534,8 @@
 
             # Failures
             'url-fail01': ('{% load url from future %}{% url %}', {}, template.TemplateSyntaxError),
-            'url-fail02': ('{% load url from future %}{% url "no_such_view" %}', {}, (urlresolvers.NoReverseMatch, urlresolvers.NoReverseMatch, template.TemplateSyntaxError)),
-            'url-fail03': ('{% load url from future %}{% url "regressiontests.templates.views.client" %}', {}, (urlresolvers.NoReverseMatch, urlresolvers.NoReverseMatch, template.TemplateSyntaxError)),
+            'url-fail02': ('{% load url from future %}{% url "no_such_view" %}', {}, (urlresolvers.NoReverseMatch, urlresolvers.NoReverseMatch)),
+            'url-fail03': ('{% load url from future %}{% url "regressiontests.templates.views.client" %}', {}, (urlresolvers.NoReverseMatch, urlresolvers.NoReverseMatch)),
             'url-fail04': ('{% load url from future %}{% url "view" id, %}', {}, template.TemplateSyntaxError),
             'url-fail05': ('{% load url from future %}{% url "view" id= %}', {}, template.TemplateSyntaxError),
             'url-fail06': ('{% load url from future %}{% url "view" a.id=id %}', {}, template.TemplateSyntaxError),
@@ -1531,9 +1543,9 @@
             'url-fail08': ('{% load url from future %}{% url "view" id="unterminatedstring %}', {}, template.TemplateSyntaxError),
             'url-fail09': ('{% load url from future %}{% url "view" id=", %}', {}, template.TemplateSyntaxError),
 
-            'url-fail11': ('{% load url from future %}{% url named_url %}', {}, (urlresolvers.NoReverseMatch, urlresolvers.NoReverseMatch, template.TemplateSyntaxError)),
-            'url-fail12': ('{% load url from future %}{% url named_url %}', {'named_url': 'no_such_view'}, (urlresolvers.NoReverseMatch, urlresolvers.NoReverseMatch, template.TemplateSyntaxError)),
-            'url-fail13': ('{% load url from future %}{% url named_url %}', {'named_url': 'regressiontests.templates.views.client'}, (urlresolvers.NoReverseMatch, urlresolvers.NoReverseMatch, template.TemplateSyntaxError)),
+            'url-fail11': ('{% load url from future %}{% url named_url %}', {}, (urlresolvers.NoReverseMatch, urlresolvers.NoReverseMatch)),
+            'url-fail12': ('{% load url from future %}{% url named_url %}', {'named_url': 'no_such_view'}, (urlresolvers.NoReverseMatch, urlresolvers.NoReverseMatch)),
+            'url-fail13': ('{% load url from future %}{% url named_url %}', {'named_url': 'regressiontests.templates.views.client'}, (urlresolvers.NoReverseMatch, urlresolvers.NoReverseMatch)),
             'url-fail14': ('{% load url from future %}{% url named_url id, %}', {'named_url': 'view'}, template.TemplateSyntaxError),
             'url-fail15': ('{% load url from future %}{% url named_url id= %}', {'named_url': 'view'}, template.TemplateSyntaxError),
             'url-fail16': ('{% load url from future %}{% url named_url a.id=id %}', {'named_url': 'view'}, template.TemplateSyntaxError),
Index: tests/regressiontests/templates/nodelist.py
===================================================================
--- tests/regressiontests/templates/nodelist.py	(revision 16772)
+++ tests/regressiontests/templates/nodelist.py	(working copy)
@@ -2,6 +2,7 @@
 from django.template import VariableNode, Context, TemplateSyntaxError
 from django.template.loader import get_template_from_string
 from django.utils.unittest import TestCase
+from django.test.utils import override_settings
 
 class NodelistTest(TestCase):
 
@@ -35,19 +36,16 @@
     Checks whether index of error is calculated correctly in
     template debugger in for loops. Refs ticket #5831
     """
-    def setUp(self):
-        self.old_template_debug = settings.TEMPLATE_DEBUG
-        settings.TEMPLATE_DEBUG = True
-
-    def tearDown(self):
-        settings.TEMPLATE_DEBUG = self.old_template_debug
-
+    @override_settings(DEBUG=True, TEMPLATE_DEBUG = True)
     def test_correct_exception_index(self):
-        tests = [
-            ('{% load bad_tag %}{% for i in range %}{% badsimpletag %}{% endfor %}', (38, 56)),
-            ('{% load bad_tag %}{% for i in range %}{% for j in range %}{% badsimpletag %}{% endfor %}{% endfor %}', (58, 76)),
-            ('{% load bad_tag %}{% for i in range %}{% badsimpletag %}{% for j in range %}Hello{% endfor %}{% endfor %}', (38, 56)),
-            ('{% load bad_tag %}{% for i in range %}{% for j in five %}{% badsimpletag %}{% endfor %}{% endfor %}', (38, 57)),
+        '''
+        Looks at an exception page and confirms that the information about the source of an error that occurs during template rendering appears in the appropriate location.
+        '''
+        tests = [ #In each case, we have template contents and the lines at which we expect the template error information to occur.
+            ('{% load bad_tag %}{% for i in range %}{% badsimpletag %}{% endfor %}', (18, 38)),
+            ('{% load bad_tag %}{% for i in range %}{% for j in range %}{% badsimpletag %}{% endfor %}{% endfor %}', (18, 38)),
+            ('{% load bad_tag %}{% for i in range %}{% badsimpletag %}{% for j in range %}Hello{% endfor %}{% endfor %}', (18, 38)),
+            ('{% load bad_tag %}{% for i in range %}{% for j in five %}{% badsimpletag %}{% endfor %}{% endfor %}', (18, 38)),
             ('{% load bad_tag %}{% for j in five %}{% badsimpletag %}{% endfor %}', (18, 37)),
         ]
         context = Context({
@@ -58,7 +56,7 @@
             template = get_template_from_string(source)
             try:
                 template.render(context)
-            except TemplateSyntaxError, e:
-                error_source_index = e.source[1]
+            except (RuntimeError, TypeError), e:
+                error_source_index = e.django_template_source[1]
                 self.assertEqual(error_source_index,
                                  expected_error_source_index)
