$ git clone -n https://src.fedoraproject.org/rpms/tcalc.git /var/lib/mock/f40-build-2216316-52488/root/chroot_tmpdir/scmroot/tcalc
Cloning into '/var/lib/mock/f40-build-2216316-52488/root/chroot_tmpdir/scmroot/tcalc'...
$ git fetch origin c6151b436cd3c7a6faa5f73de32545431740edb9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/tcalc
 * [new ref]         c6151b436cd3c7a6faa5f73de32545431740edb9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c6151b4 Rework spec to comply with the latest guidelines