$ git clone -n https://src.fedoraproject.org/rpms/rust-tame-index.git /var/lib/mock/f42-build-side-1-3589192-46954/root/chroot_tmpdir/scmroot/rust-tame-index
Cloning into '/var/lib/mock/f42-build-side-1-3589192-46954/root/chroot_tmpdir/scmroot/rust-tame-index'...
$ git fetch origin d41cfd3792209b74c386faa5b900adac5a43dfc7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-tame-index
 * [new ref]         d41cfd3792209b74c386faa5b900adac5a43dfc7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d41cfd3 Update to version 0.18.1; Fixes RHBZ#2346776