$ git clone -n https://src.fedoraproject.org/rpms/rust-cargo-c.git /var/lib/mock/f42-build-side-1-3512476-46069/root/chroot_tmpdir/scmroot/rust-cargo-c
Cloning into '/var/lib/mock/f42-build-side-1-3512476-46069/root/chroot_tmpdir/scmroot/rust-cargo-c'...
$ git fetch origin e4f6b1869ff979541b9e271a7a73665296a2068f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-cargo-c
 * [new ref]         e4f6b1869ff979541b9e271a7a73665296a2068f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e4f6b18 Update to version 0.10.11+cargo-0.86.0; Fixes RHBZ#2292775