checkout -f: allow ignoring unmerged paths when checking out of the index
Earlier we made "git checkout $pathspec" to atomically refuse
the operation of $pathspec matched any path with unmerged
stages. This patch allows:
$ git checkout -f a b c
to ignore, instead of error out on, such unmerged paths. The
fix to prevent checkout of an unmerged path from random stages
is still there.
Signed-off-by: Junio C Hamano <gitster@pobox.com>