cleanup: consistently use local variable instead of attribute

Signed-off-by: Jelmer Vernooij <jelmer@samba.org>
send_pack: simplify filtering of unsupported ref deletions

The previous implementation used filter() over a nontrivial nested
function with side-effects. A simple loop is a bit more readable.

Signed-off-by: Jelmer Vernooij <jelmer@samba.org>
send_pack: simplify condition guarding whether a pack is sent

Signed-off-by: Jelmer Vernooij <jelmer@samba.org>
Add docstrings for Commit.extra and Commit.parents.
Support 'gpgsig' property in Commit objects.
Test ProtocolGraphWalker.all_wants_satisfied rather than private
_is_satisfied.
Add missing underscore in test name.
Factor out all_wants_satisfied.
Merge remote-tracking branch 'origin/python2.6' into python2.6

* origin/python2.6:
  Don't use ConfigParser(allow_no_value=True) as it's not supported on Python2.6
  Add unittest2 to tests_require on python2.6
  Fix version check.
  Fix travis on python2.6
  Reintroduce Python2.6 support.
Add NEWS item for python2.6 support.