extensions.disabled: return {} instead of None no extensions are disabled

merge: respect bookmarks during merge Bookmarks will behave more like named branches when merge tries to pick a revision to merge. Bookmarks now to respect the current bookmarks. Bookmarks will not accidentally merged with unnamed heads or other bookmarks. However merge can pick heads with diverging bookmarks and pick those automatically. We end up with two cases for picking a revision to merge: (1) In case of an current bookmark, merge can pick a branch head that has a diverged bookmark (2) In case of no current bookmark, merge can pick a branch head that does not have a bookmark.

localrepo: introduce bookmarkheads Similar to branch heads we introduce the notion of bookmarkheads. Bookmarkheads are changests that are bookmarked with the given bookmark or a diverged version

bookmarks: delete divergent bookmarks on merge

check-code: ignore naked excepts with a "re-raise" comment This also promotes the naked except check from a warning to an error.

check-code: improve detection of naked except clauses

cleanup: replace more naked excepts with more specific ones

check-code: promote 80+ character line warning to an error

cmdutil: use filectx.cmp() in amend()

largefiles: optimize performance when updating (issue3440) Previously, when updating, cachelfiles was called blindly on all largefiles in the repository at the revision being updated to, despite the fact that a list of which largefiles needs to be updated has already been collected. This optimization constrains the cachelfiles call to only the largefiles that need to be updated. On a repository with about 80 largefiles, updating between two revisions that only change one largefile goes from approximately 6.7 seconds to 3.3 seconds.