$ git clone -n https://src.fedoraproject.org/rpms/rust-bpaf.git /var/lib/mock/f42-build-side-1-3540388-46574/root/chroot_tmpdir/scmroot/rust-bpaf
Cloning into '/var/lib/mock/f42-build-side-1-3540388-46574/root/chroot_tmpdir/scmroot/rust-bpaf'...
$ git fetch origin 3a87551914e8dcc086eba9f2e6f909b4adeb4445:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-bpaf
 * [new ref]         3a87551914e8dcc086eba9f2e6f909b4adeb4445 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3a87551 Update to version 0.9.19; Fixes RHBZ#2342048