[patch] newforms.URLField() does not validate with both required=False and verify_exists=True

[zendak]

The following newforms field will prevent its form from validating if given a "False" value (empty string or None):

url = newforms.URLField(required=False, verify_exists=True)

This combination of required and verify_exists causes a conflict. Note that for a corresponding model.URLField(blank=True, verify_exists=True) there is no such conflict when accessed through the Admin.

[astrec]

replacement patch - non-relative header, and .diff extension

[Adrian Holovaty]

(In [4313]) Fixed #3281 -- newforms: URLField now works properly with required=False and verify_exists=True together. Thanks, zendak

[zendak]

Thanks for the patch, astrec, you beat me to it. Works perfectly now.