$ git clone -n https://src.fedoraproject.org/rpms/rust-grep.git /var/lib/mock/f45-build-42150-791/root/chroot_tmpdir/scmroot/rust-grep
Cloning into '/var/lib/mock/f45-build-42150-791/root/chroot_tmpdir/scmroot/rust-grep'...
$ git fetch origin 9b0a32788842eb122e04f9391828e3aa6cc889e5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-grep
 * [new ref]         9b0a32788842eb122e04f9391828e3aa6cc889e5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9b0a327 Update to version 0.4.1; Fixes RHBZ#2404334