Some minor changes to the `patch_vary_headers` function:  * Replaced a for loop with a list comprehension.  * Used a set instead of a dict with dummy values.  * Used a bit more readable variable names.
Some minor changes to the `patch_vary_headers` function:
 * Replaced a for loop with a list comprehension.
 * Used a set instead of a dict with dummy values.
 * Used a bit more readable variable names.

--HG--
extra : convert_revision : svn%3Abcc190cf-cafb-0310-a4f2-bffc1f526a37/django/trunk%406698

Belgabor/django,Belgabor/django,Belgabor/django