$ git clone -n https://src.fedoraproject.org/rpms/rust-etcetera.git /var/lib/mock/f39-build-1602550-38571/root/chroot_tmpdir/scmroot/rust-etcetera
Cloning into '/var/lib/mock/f39-build-1602550-38571/root/chroot_tmpdir/scmroot/rust-etcetera'...
$ git fetch origin 62db776ce1ccdc4cf4d18fc8d26f37e0e243c8fd:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-etcetera
 * [new ref]         62db776ce1ccdc4cf4d18fc8d26f37e0e243c8fd -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 62db776 Third times the charm (fedora#2240793)