Ticket #11052: 11052.promote_alias_lhs.diff

django/db/models/sql/query.py

@@ -1074 +1074 @@
 
         Returns True if the join was promoted.
         """
-        if ((unconditional or self.alias_map[alias][NULLABLE]) and
+        nullable = self.alias_map[alias][NULLABLE]
+        lhs_alias = self.alias_map[alias][LHS_ALIAS]
+        if lhs_alias:
+            nullable = nullable or self.alias_map[lhs_alias][NULLABLE]
+        if ((unconditional or nullable) and
                 self.alias_map[alias][JOIN_TYPE] != self.LOUTER):
             data = list(self.alias_map[alias])
             data[JOIN_TYPE] = self.LOUTER