_ssh: fix trailing whitespace

--HG--
extra : rebase_source : 20df30c428cc6220b4e8f2db15ecccdf7ef50673
_ssh: remove stray print

--HG--
extra : rebase_source : 9acce8d1926b0eb60f790bd63d0d94f1e49cd211
hgrepo: catch NotGitRepository and turn it into abort
setup: require newer dulwich so we can always pass an opener to HttpGitClient

--HG--
extra : histedit_source : b2900f4cf3de676865aa6c4988ee9e0655f7b21b
git_handler: drop lots of compat cruft for old dulwich versions

--HG--
extra : histedit_source : 31351f303c9b11bf426388dbfb8866a20e0707d4
git_handler: attempt to advertise a slightly better user-agent

This causes github to actually respect us as a git client. I still
maintain the user-agent sniffing is silly, but at least now it works.

--HG--
extra : amend_source : a34da627a48be6e9eaecf11811bc4ffa39a124c1
extra : histedit_source : b8511ac4a11e03c02acfc76de0bdf30b0c9a68f0
tests: adapt for hg 3.1 output changes

--HG--
extra : histedit_source : 14d297a37df5671161a41b2b09db3b3834527fee
Mark hg 3.1 as supported as well.

--HG--
extra : histedit_source : dd2eadca7b9a2d263d116c037b486a23534f3e52