$ git clone -n https://src.fedoraproject.org/rpms/python-mechanicalsoup.git /var/lib/mock/f43-build-60984197-6587238/root/chroot_tmpdir/scmroot/python-mechanicalsoup
Cloning into '/var/lib/mock/f43-build-60984197-6587238/root/chroot_tmpdir/scmroot/python-mechanicalsoup'...
$ git fetch origin 3802f2e861f80a0b38702a8af57cab0cb88318e3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/python-mechanicalsoup
 * [new ref]         3802f2e861f80a0b38702a8af57cab0cb88318e3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3802f2e Update to latest upstream release (closes rhbz#2369327)