$ git clone -n https://src.fedoraproject.org/rpms/mozjs91.git /var/lib/mock/f39-build-2339755-59665/root/chroot_tmpdir/scmroot/mozjs91
Cloning into '/var/lib/mock/f39-build-2339755-59665/root/chroot_tmpdir/scmroot/mozjs91'...
$ git fetch origin 5ca42ab7d2a6893182e877233f922b573418f388:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mozjs91
 * [new ref]         5ca42ab7d2a6893182e877233f922b573418f388 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5ca42ab Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild