$ git clone -n https://src.fedoraproject.org/rpms/rust-errno.git /var/lib/mock/f42-build-60965141-6586802/root/chroot_tmpdir/scmroot/rust-errno
Cloning into '/var/lib/mock/f42-build-60965141-6586802/root/chroot_tmpdir/scmroot/rust-errno'...
$ git fetch origin 74989c3aea24ccadde4a76ab977e616bcab120b0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-errno
 * [new ref]         74989c3aea24ccadde4a76ab977e616bcab120b0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 74989c3 Update to version 0.3.13