$ git clone -n https://src.fedoraproject.org/rpms/rust-errno.git /var/lib/mock/f42-build-side-1-3539964-46572/root/chroot_tmpdir/scmroot/rust-errno
Cloning into '/var/lib/mock/f42-build-side-1-3539964-46572/root/chroot_tmpdir/scmroot/rust-errno'...
$ git fetch origin 4e8a2b3fcaf5d179489a0b0eecc467c2ed22a36d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-errno
 * [new ref]         4e8a2b3fcaf5d179489a0b0eecc467c2ed22a36d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4e8a2b3 Update to version 0.3.12; Fixes RHBZ#2366649