obscache: directly allocate zeroed bytearray This is much faster that incrementally appending to it. On mozilla central without obsolescence markers this move full cache building from 0.3s to nothing visible.

obscache: plug on core 'update cache' method if available I was planning to have this implemented in core but since things are not getting in I'm updating evolve.

obscache: pre-indent code This will make the next changeset clearer.

fix: fix _headssummary call to orig 65cf338258d2 one of two orig call wasn't compatible with mercurial version < 4.3, fix it.

test-update: update hg update output in test files Following hg revision 1b5c61d38a52, hg update now show the commit to which we updated in case of multiple heads. test-obsolete.t and test-sharing.t falls in these situations, acknowledge the new outputted line.

test-drop: all obsmarkers are now dropped Previously, hg drop may leave some obsmarkers behind, like with temporary amend commit. Following mercurial revision 71eb6a098315, strip now correctly remove the associated obsmarkers and as drop is also calling strip, the bug is now resolved.