[1.7.x] Simplified handling of use_debug_cursor.
[1.7.x] Simplified handling of use_debug_cursor.

Turned it from a tri-valued boolean into a regular boolean.

Backport of 127218b9 from master.

jyotsna1820/django,jyotsna1820/django,jyotsna1820/django,oscaro/django,oscaro/django,oscaro/django,jyotsna1820/django,oscaro/django