$ git clone -n https://src.fedoraproject.org/rpms/rust-cargo-c.git /var/lib/mock/f42-build-side-1-3586538-46923/root/chroot_tmpdir/scmroot/rust-cargo-c
Cloning into '/var/lib/mock/f42-build-side-1-3586538-46923/root/chroot_tmpdir/scmroot/rust-cargo-c'...
$ git fetch origin b01735b5c039070f4b2bf4e9cc249e29c4710698:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-cargo-c
 * [new ref]         b01735b5c039070f4b2bf4e9cc249e29c4710698 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b01735b Update to version 0.10.12+cargo-0.87.0; Fixes RHBZ#2357593