Fix group clustering, it was not clustering child groups.
Fix group clustering, it was not clustering child groups.

Clustering a group requires recursively clustering its child groups,
otherwise we are only clustering the root group.

pmuetschard/gapid,baldwinn860/gapid,pmuetschard/gapid,Qining/gapid,Qining/gapid,Qining/gapid,google/gapid,dsrbecky/gapid,google/agi,baldwinn860/gapid,baldwinn860/gapid,google/agi,Qining/gapid,google/agi,baldwinn860/gapid,google/agi,dsrbecky/gapid,google/agi,pmuetschard/gapid,pmuetschard/gapid,dsrbecky/gapid,pmuetschard/gapid,Qining/gapid,dsrbecky/gapid,pmuetschard/gapid,dsrbecky/gapid,google/gapid,Qining/gapid,google/gapid,google/agi,pmuetschard/gapid,baldwinn860/gapid,Qining/gapid,pmuetschard/gapid,google/gapid,dsrbecky/gapid,google/gapid,google/agi,dsrbecky/gapid,google/gapid,baldwinn860/gapid,google/gapid,google/gapid,baldwinn860/gapid,baldwinn860/gapid,google/agi,dsrbecky/gapid,Qining/gapid