$ git clone -n https://src.fedoraproject.org/rpms/composer.git /var/lib/mock/f42-build-side-1-3502102-45977/root/chroot_tmpdir/scmroot/composer
Cloning into '/var/lib/mock/f42-build-side-1-3502102-45977/root/chroot_tmpdir/scmroot/composer'...
$ git fetch origin a6ca5074a589b67a228ec0e47afe562adaf8231c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/composer
 * [new ref]         a6ca5074a589b67a228ec0e47afe562adaf8231c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a6ca507 v2.8.8