Use with statement rather than try: finaly: x.close().
Travis: use system site packages in virtualenv.
Use stderr.splitlines rather than Popen(universal_newlines=True)

The reason for this is that universal_newlines takes the Popen files out of
bytes mode on python3.
Merge branch 'travis' of git://github.com/garyvdm/dulwich
Merge branch 'with' of git://github.com/garyvdm/dulwich
Remove tags from list of missing documentation
Fix typo in method description
Remove unused import.
Check for bytes rather than str.
Use bytes literals instead of string literals.
Use six.moves.
Apply libmodernize.fixes.fix_dict.

(Exclude dulwich.objects)
Use six.byte2int, .indexbytes, and .iterbytes.
Fix PackBasedObjectStore.packs.
String stuff (It's late.)
stuff