copies: split creation of the graph and actual checking again
The re-install the old split. It will be necessary to test that the upgrade
process produced a functionally identical result. It will be useful to detect
case where the metadata we look at identical, but some other items we did not
checked are missing.
(spoiler: we will find some bug)
Differential Revision: https://phab.mercurial-scm.org/D9195
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
difficult on Windows), please at least run `contrib/check-code.py` on
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).