Boris Feld <boris.feld@octobus.net> [Wed, 21 Nov 2018 21:11:47 +0000] rev 40805
perf: start from an existing branchmap if possible
If the --base set if a superset of one of the cached branchmap, we should use as
a starting point. This greatly help the overall runtime of
`hg perfbranchmapupdate`
For example, for a repository with about 500 000 revisions, using this trick
make the command runtime move from about 200 second to about 10 seconds. A 20x
gain.