Add more sanity checks for metric dict merger.
Add more sanity checks for metric dict merger.

sorgerlab/belpy,johnbachman/indra,sorgerlab/indra,sorgerlab/belpy,sorgerlab/belpy,sorgerlab/indra,sorgerlab/indra,johnbachman/indra,bgyori/indra,bgyori/indra,bgyori/indra,johnbachman/indra