perf: add a `clear-revlogs` flag to `perftags` This flag (on by default) makes it possible to disable the refresh of the changelog and revlog. This is useful to check for the time spent in the core tags logic without the associated side effects. Usually, these side effects are shared with other logics (eg: bookmarks). Example output in my Mercurial repository $ hg perftags ! wall 0.017919 comb 0.020000 user 0.020000 sys 0.000000 (best of 141) $ hg perftags --no-clear-revlogs ! wall 0.012982 comb 0.010000 user 0.010000 sys 0.000000 (best of 207)