$ git clone -n https://src.fedoraproject.org/rpms/R-inline.git /var/lib/mock/f42-build-side-1-3500324-45970/root/chroot_tmpdir/scmroot/R-inline
Cloning into '/var/lib/mock/f42-build-side-1-3500324-45970/root/chroot_tmpdir/scmroot/R-inline'...
$ git fetch origin 854cc4936e2da926c252c6f69f528d9786d133a2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-inline
 * [new ref]         854cc4936e2da926c252c6f69f528d9786d133a2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 854cc49 R-maint-sig mass rebuild