$ git clone -n https://src.fedoraproject.org/rpms/tinygo.git /var/lib/mock/f40-build-804380-144509/root/chroot_tmpdir/scmroot/tinygo
Cloning into '/var/lib/mock/f40-build-804380-144509/root/chroot_tmpdir/scmroot/tinygo'...
$ git fetch origin 1539b445c8fda1739f5b188fd02e6912c6271e38:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/tinygo
 * [new ref]         1539b445c8fda1739f5b188fd02e6912c6271e38 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1539b44 Allow an older version of golang.org/x/tools