Before this patch undo.bookmarks was created on bookmarks write and
not with other transaction-related files. There were two issues: first
is that if you have changed bookmarks few times after a transaction
happened, rollback will give you a state which can point to
non-existing revision. Second is that if you have not changed
bookmarks after a transaction, rollback will touch your state anyway.
This change also adds `localrepo._writejournal` method, which can be
used by other extensions to save their transaction-related backup in
right time.
The generation of cache files like tags.cache and branchheads.cache is not an
actual reflection of things changing in the whole of the .hg directory (like eg
a commit or a rebase or something) but instead these cache files are just part
of bookkeeping. As such its convienant to allow various clients to ignore file
events to do with these cache files which would otherwise cause a double
refresh. Eg one refresh might occur after a commit, but the act of refreshing
after the commit would cause Mercurial to generate a new branchheads.cache which
would then cause a second refresh, for clients.
However if these cache files are moved into a directory like eg .hg/cache/ then
GUI clients on OSX (and possibly other platforms) can happily ignore file events
in this cache directory.
