$ git clone -n https://src.fedoraproject.org/rpms/xorg-x11-drv-nouveau.git /var/lib/mock/f41-build-857477-168112/root/chroot_tmpdir/scmroot/xorg-x11-drv-nouveau
Cloning into '/var/lib/mock/f41-build-857477-168112/root/chroot_tmpdir/scmroot/xorg-x11-drv-nouveau'...
$ git fetch origin 3c19e751f6f6e1f1ccd84d49c7240884af5b4435:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xorg-x11-drv-nouveau
 * [new ref]         3c19e751f6f6e1f1ccd84d49c7240884af5b4435 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3c19e75 Clean up SPEC file