Not everyone got a smooth migration for git/subversion from dev-util
to dev-vcs, so add a hook to manually unmerge the old versions. The
newer packages should recover gracefully after that.
BUG=chromium-os:24360
TEST=build_packages ran ver 23 upgrade and continued on
Change-Id: I0b56f0f0a8b8a7ebd64a4a664e5524f0b7828791
Reviewed-on: https://gerrit.chromium.org/gerrit/13663
Reviewed-by: Doug Anderson <dianders@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Ready: Doug Anderson <dianders@chromium.org>
