formatter: make labels work with templated output
To describe the bug this fix is addressing, one can do
``$ hg status -T "{label('red', path)}\n" --color=debug``
and observe that the label is not applied before my fix and applied with it.
$ hg init
$ touch unknown
$ touch a
$ hg add a
$ hg ci -m "1"
$ touch b
$ hg add b
$ hg ci -m "2"
Should show unknown
$ hg status
? unknown
$ hg revert -r 0 --all
removing b
Should show unknown and b removed
$ hg status
R b
? unknown
Should show a and unknown
$ ls
a
unknown