$ git clone -n https://src.fedoraproject.org/rpms/rust-signature.git /var/lib/mock/f38-build-side-42-init-devel-1395833-31050/root/chroot_tmpdir/scmroot/rust-signature
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-1395833-31050/root/chroot_tmpdir/scmroot/rust-signature'...
$ git fetch origin b15c855e69045cd8fca08a734ed98db1047ce0fd:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-signature
 * [new ref]         b15c855e69045cd8fca08a734ed98db1047ce0fd -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b15c855 Update to version 2.1.0; Fixes RHBZ#2161097