transaction: always remove empty journal on abort
When transactions without entries were aborted, the journal (of size 0) was not
unlinked, which prevents subsequent operations until hg recover is run on the
repository.
We also make sure the journal is unlinked when committing, even if the provided
hook doesn't do so.
adding a
abort: abandoned transaction found - run hg recover!
rolling back interrupted transaction
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
% check that zero-size journals are correctly aborted
adding changesets
abort: Permission denied