Fixes #54 | option branch_bookmark_suffix doesn't move bookmarks along

Test case based on the one proposed by David Carr at
https://bitbucket.org/durin42/hg-git/issue/54/with-option-branch_bookmark_suffix-set
Make the path part of URL contain a leading slash only if it's not followed by tilde. (issue #71)

--HG--
extra : rebase_source : 25455ed923f9d7070cc76b681c5986276525036b
extra : amend_source : a619dd9b0eaca6d32052b5b0fec9c2702277d641
git_handler: skip exporting hg tags whose names are not valid as git tag name

--HG--
extra : histedit_source : f3426411e7d4baae8b07c4e0998d721b8ad4531f%2Cb7aea4a71b7ce6c045e23c612ea9b48777edd918
test-tree-decomposition: work around git command format changes
Update test output to handle 65d8a43b adding some more objects.
merge
test-subrepos: cope with unsorted output in .hgsub