UnboundLocalError: local variable 'sql' referenced before assignment

[Oscar Esgalha]

I have a model similar to this one:

class Sale(models.Model):
    price = models.DecimalField(max_digits=8, decimal_places=2)
    delivery_date = models.DateTimeField()

And I want to get the sum of sales per month, so I tried this:

models.Sale.objects.datetimes('delivery_date', 'month').annotate(Sum('price'))

Since datetimes returns a new QuerySet, I expected that code would work, but I stumbled on this error message:

Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/home/vagrant/.virtualenvs/awesomeapp/local/lib/python2.7/site-packages/django/db/models/query.py", line 116, in __repr__
    data = list(self[:REPR_OUTPUT_SIZE + 1])
  File "/home/vagrant/.virtualenvs/awesomeapp/local/lib/python2.7/site-packages/django/db/models/query.py", line 141, in __iter__
    self._fetch_all()
  File "/home/vagrant/.virtualenvs/awesomeapp/local/lib/python2.7/site-packages/django/db/models/query.py", line 966, in _fetch_all
    self._result_cache = list(self.iterator())
  File "/home/vagrant/.virtualenvs/awesomeapp/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 1130, in results_iter
    for rows in self.execute_sql(MULTI):
  File "/home/vagrant/.virtualenvs/awesomeapp/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 775, in execute_sql
    sql, params = self.as_sql()
  File "/home/vagrant/.virtualenvs/awesomeapp/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 133, in as_sql
    grouping, gb_params = self.get_grouping(having_group_by, ordering_group_by)
  File "/home/vagrant/.virtualenvs/awesomeapp/local/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 586, in get_grouping
    if sql not in seen:
UnboundLocalError: local variable 'sql' referenced before assignment

So I took a look at the source code:
​https://github.com/django/django/blob/1.7.3/django/db/models/sql/compiler.py#L586

And if I read it correctly: if the condition in line 582 is sufficed, then the var 'sql' is indeed unassigned in the line 586.

I'm using python 2.7.6 and Django 1.7.3
The database is MySQL 5.5

[Peter Inglesby]

This is fixed in 1.8, and was fixed by ​this commit.