tests: run "cwd was removed" test only if cwd can actually be removed
On some platforms, cwd can't be removed. In which case, util.unlinkpath()
continues with no error since the failure of directory removal isn't critical.
So it doesn't make sense to run the test added by
90a6c18a7c1d on those
platforms. OTOH, we need to run the test in test-rebase-scenario-global.t
since the repository is referenced after that.
#require docutils gettext
$ $TESTDIR/check-gendoc ro
checking for parse errors