$ git clone -n https://src.fedoraproject.org/rpms/rust-v_frame.git /var/lib/mock/f42-build-side-1-3511983-46060/root/chroot_tmpdir/scmroot/rust-v_frame
Cloning into '/var/lib/mock/f42-build-side-1-3511983-46060/root/chroot_tmpdir/scmroot/rust-v_frame'...
$ git fetch origin df8bed442eeaff02b27a0cb535ef094b474470c2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-v_frame
 * [new ref]         df8bed442eeaff02b27a0cb535ef094b474470c2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at df8bed4 Update to version 0.3.8; Fixes RHBZ#2268919