$ git clone -n https://src.fedoraproject.org/rpms/mesa.git /var/lib/mock/f40-build-1830766-24926/root/chroot_tmpdir/scmroot/mesa
Cloning into '/var/lib/mock/f40-build-1830766-24926/root/chroot_tmpdir/scmroot/mesa'...
$ git fetch origin ce89d320284bef0df5d61f47d37d1b7a1f25c753:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mesa
 * [new ref]         ce89d320284bef0df5d61f47d37d1b7a1f25c753 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ce89d32 Merge branch 'rawhide' into f40