cmdutil: fix an uninitialize variable usage in clearunfinished()
I happened to notice that PyCharm flagged this while looking for something else.
I'm pretty sure it meant to check the current state in the iteration, and not
keep reusing the last one in the previous iteration.
Differential Revision: https://phab.mercurial-scm.org/D10459
[workspace]
members = ["hg-core", "hg-cpython", "rhg"]
exclude = ["chg", "hgcli"]