$ git clone -n https://src.fedoraproject.org/rpms/grfcodec.git /var/lib/mock/f41-build-757238-13423/root/chroot_tmpdir/scmroot/grfcodec
Cloning into '/var/lib/mock/f41-build-757238-13423/root/chroot_tmpdir/scmroot/grfcodec'...
$ git fetch origin a6e346140dffe11b2a0e352917273b3e427ff9e3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/grfcodec
 * [new ref]         a6e346140dffe11b2a0e352917273b3e427ff9e3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a6e3461 Eliminate use of obsolete %patchN syntax (#2283636)