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.
# name space package to host third party extensions
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)