mq: comply with filtering when injecting fake tags (issue3812)
mq was injecting fake tags whenever the revisions were accessible
to the filtering level.
This issue impacts hgweb since it's common to have "secret" mq
patches. As secret changesets are filtered by hgweb, the tags
computation could break.
Testing that hghave does not crash when checking features
$ "$TESTDIR/hghave" --test-features 2>/dev/null