$ git clone -n https://src.fedoraproject.org/rpms/rust-fs4.git /var/lib/mock/f40-build-1194298-22252/root/chroot_tmpdir/scmroot/rust-fs4
Cloning into '/var/lib/mock/f40-build-1194298-22252/root/chroot_tmpdir/scmroot/rust-fs4'...
$ git fetch origin 660afaf5543f4dc31201821aaa6d761e83a913b2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-fs4
 * [new ref]         660afaf5543f4dc31201821aaa6d761e83a913b2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 660afaf Update to version 0.8.4; Fixes RHBZ#2291278