templatekw: cache mergestate even if merge is not ongoing While playing with eBPF, I noticed .hg/merge/state{,2} files were tried to open() for each revision. That's not healthy. Let's cache the "inactive" state as well.

revset: remove explicit sort() from unstable() The instability should be dealt with by baseset.__init__(), and the returned smartset is ordered by 'subset &' anyway.