test-transaction-safety: perform the test on a filelog
This test previously checked the transaction safety of splitting the changelog.
The changelog is a special case, with delayed/diverted writes and we will stop
inlining it soon. So we keep testing that transaction is safe around inline on
another revlog type : a filelog.
Minor comestic adjustement will be done in the next changesets.
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).