Given a URL pattern of the form ((?P<capture>[a-z]+)/)?, a call to

reverse with the kwargs {'capture': 'foo'} will result in a

NoReverseMatch exception. This occurs because the capture param gets

hidden behind a positional parameter and Django will expect the

positional parameter intead of the named parameter for the call to

reverse. We now no longer use capturing groups -- we explicltly mark the

outer group as non-capturing (e.g. (?:(?P<capture>[a-z]+)/)?, which

works as expected.
We previously were also using capturing groups in the form of

?(P<capture>(a|b)). Not only will a non-capturing group work here, the

group isn't needed at all: a expression of the form (?P<capture>a|b)

is sufficient. All instances of this have been fixed.

Ran unit tests.
Viewed the diff fragment view for an interdiff.
Viewed the e-mail preview views in html and text formats.