$ git clone -n https://src.fedoraproject.org/rpms/rust-serde_ignored.git /var/lib/mock/f40-build-2251173-54117/root/chroot_tmpdir/scmroot/rust-serde_ignored
Cloning into '/var/lib/mock/f40-build-2251173-54117/root/chroot_tmpdir/scmroot/rust-serde_ignored'...
$ git fetch origin 7d4da552dd95fbb1c228530d95cd4c513e06f9a5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-serde_ignored
 * [new ref]         7d4da552dd95fbb1c228530d95cd4c513e06f9a5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7d4da55 Update to version 0.1.10; Fixes RHBZ#2256498