If a branch points to the working-copy commit, it will automatically
get updated when the working copy is snapshotted. However, it turns
out that we don't automatically export the change to Git when running
in a colocated working copy (nor in a non-colocated working copy, but
that shouldn't be surprising). The change will not get exported until
a non-snapshot operation runs. We noticed this bug in @hooper's repo
today.