$ git clone -n https://src.fedoraproject.org/rpms/python-flask.git /var/lib/mock/f40-build-2213651-52345/root/chroot_tmpdir/scmroot/python-flask
Cloning into '/var/lib/mock/f40-build-2213651-52345/root/chroot_tmpdir/scmroot/python-flask'...
$ git fetch origin 088644968775eec2a08857fdb81eaba3941f99d2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/python-flask
 * [new ref]         088644968775eec2a08857fdb81eaba3941f99d2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0886449 Update to 3.0.0 (fixes RHBZ#2189630)