$ git clone -n https://github.com/fedora-riscv/mozjs91.git /var/lib/mock/f38-build-side-42-init-devel-613206-26293/root/chroot_tmpdir/scmroot/mozjs91
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-613206-26293/root/chroot_tmpdir/scmroot/mozjs91'...
$ git fetch origin 04e3525278f9e68d42a867757e1ef3182506a2bf:KOJI_FETCH_HEAD
From https://github.com/fedora-riscv/mozjs91
 * [new ref]         04e3525278f9e68d42a867757e1ef3182506a2bf -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 04e3525 Merge remote-tracking branch 'fedoraproject/f38' into f38-rv64