localrepo: use workingctx for validation in commit
This changes localrepo.commit to use the workingctx it creates form
the munged output of localrepo.status while running some precommit
validation. Specifically, it uses functions that were already present
on the workingctx. I believe this is a net readabilty improvement,
and that this makes these lines consistent with the refactoring in a
subsequent patch that pulls some of the validation logic into
workingctx so that it can be reused elsewhere.
$ hg init
$ echo a > a
$ hg ci -Am t
adding a
$ hg mv a b
$ hg ci -Am t1
$ hg debugrename b
b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3
$ hg mv b a
$ hg ci -Am t2
$ hg debugrename a
a renamed from b:37d9b5d994eab34eda9c16b195ace52c7b129980
$ hg debugrename --rev 1 b
b renamed from a:b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3