changelog-v2: add a configuration to disable rank computation
We encountered a graph where rank computation was pathologically slow. We add an
option to disable this computation while this is getting fixed.
Disabling the rank computation should allow for testing other changelog-v2
features undisturbed (like changeset-based copy tracing).
I am purposely not adding a test for the new non-default code path, as this is
a temporary work around of an experimental feature.
Our full contribution guidelines are in our wiki, please see:
https://www.mercurial-scm.org/wiki/ContributingChanges
If you just want a checklist to follow, you can go straight to
https://www.mercurial-scm.org/wiki/ContributingChanges#Submission_checklist
If you can't run the entire testsuite for some reason (it can be
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any files you've modified and run `python contrib/check-commit` on any
commits you've made (for example, `python contrib/check-commit
273ce12ad8f1` will report some style violations on a very old commit).