$ git clone -n https://src.fedoraproject.org/rpms/gjs.git /var/lib/mock/f39-build-1826437-41868/root/chroot_tmpdir/scmroot/gjs
Cloning into '/var/lib/mock/f39-build-1826437-41868/root/chroot_tmpdir/scmroot/gjs'...
$ git fetch origin 8a1deefa3375f3e31709125cf77e1f08923db97c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/gjs
 * [new ref]         8a1deefa3375f3e31709125cf77e1f08923db97c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8a1deef Rebuild against mozjs115-115.4.0-1