delta: reuse _findsnapshot call from previous stage Two different stage of the sparse-revlog logic needs the _findsnapshot data. To avoid recomputing it twice, make it possible to reuse the first computation in the second step. example affected manifest write before: 0.067141s after: 0.064252s (-5%) (total gain since start of series: 95%)

delta: have a native implementation of _findsnapshot The function might traverse a lot of revision, a native implementation get significantly faster. example affected manifest write before: 0.114989 after: 0.067141 (-42%)

transaction: do not overwrite atomic-temp files on error Even though the original files can be restored from the backup, it should be better to not write back a temporary file if we know it can be corrupted.

help: fix typo

rust: use 'impl Trait' in method argument of AncestorsIterator I just didn't know it's stabilized. Let's switch to new convenient syntax. Differential Revision: https://phab.mercurial-scm.org/D5451

rust: use .rev() for reverse range Differential Revision: https://phab.mercurial-scm.org/D5450

histedit: add warning message on editing tagged commits (issue4017) Differential Revision: https://phab.mercurial-scm.org/D5489

strip: extract bookmark movement into a separate function We will need it for the soft-strip case.

strip: compute bookmark target only if we have bookmark to move This is a small change that seems to make sense.

strip: extract code to create strip backup We will reuse this for soft stripping.