$ git clone -n https://src.fedoraproject.org/rpms/passim.git /var/lib/mock/f39-build-1640975-40160/root/chroot_tmpdir/scmroot/passim
Cloning into '/var/lib/mock/f39-build-1640975-40160/root/chroot_tmpdir/scmroot/passim'...
$ git fetch origin f5bd6e930e8f3e4fc9d96a43d22544a3388e54b2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/passim
 * [new ref]         f5bd6e930e8f3e4fc9d96a43d22544a3388e54b2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f5bd6e9 New upstream release