$ git clone -n https://src.fedoraproject.org/rpms/js-jsroot.git /var/lib/mock/f40-build-2005248-45048/root/chroot_tmpdir/scmroot/js-jsroot
Cloning into '/var/lib/mock/f40-build-2005248-45048/root/chroot_tmpdir/scmroot/js-jsroot'...
$ git fetch origin 9fddaa82b518febed57b5d60951dc70f73054578:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/js-jsroot
 * [new ref]         9fddaa82b518febed57b5d60951dc70f73054578 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9fddaa8 Update to version 7.5.3