$ git clone -n https://src.fedoraproject.org/rpms/jackson-core.git /var/lib/mock/f40-build-2363537-60368/root/chroot_tmpdir/scmroot/jackson-core
Cloning into '/var/lib/mock/f40-build-2363537-60368/root/chroot_tmpdir/scmroot/jackson-core'...
$ git fetch origin c71dbcca7e0766dfc04a6a7ee9cd3c089c327e2a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/jackson-core
 * [new ref]         c71dbcca7e0766dfc04a6a7ee9cd3c089c327e2a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c71dbcc Conditionalize arches for RHEL