pathutil: tease out a new library to break an import cycle from canonpath use

subsettable: move from repoview to branchmap, the only place it's used This is a step towards breaking an import cycle between revset and repoview. Import cycles happened to work in Python 2 with implicit relative imports, but breaks on Python 3 when we start using explicit relative imports via 2to3 rewrite rules.

obsolete: add __eq__ and __hash__ to marker to make set() deduplication work

obsolete: do not accept duplicated marker during exchange Before this patch, duplicated obsolescence markers could slip into an obstore if the bookmark was unknown locally and duplicated in the incoming obsolescence stream. Existing duplicate markers will not be automatically removed but they'll stop propagating. Having a few duplicated markers is harmless and people have been warned evolution is <blink>experimental</blink> anyway.

Merge with stable.

obsolete: stop doing membership test on list According to the Surgeon General, computer should not use list for membership testing because of the risk of being slow.

bookmarks: rewrite pushing bookmarks in "localrepository.push()" by "compare()" This patch adds "updateremote()", which uses "compare()" to compare bookmarks between the local and the remote repositories, to replace pushing local bookmarks in "localrepository.push()".

bookmarks: rewrite pushing local bookmarks in "commands.push()" by "compare()" This patch adds "pushtoremote()", which uses "compare()" to compare bookmarks between the local and the remote repositories, to replace pushing local bookmarks in "commands.push()".