Concept specifies system multiple times

[cmoesel]

When we process CodeSystem concept rules, we sometimes double-up on the system (e.g., FOO#bar from system FOO). For a real-world example, run GoFSH against mCODE's fsh-generated and you'll find stuff like:

* include http://ncithesaurus-stage.nci.nih.gov#C146985 "AJCC Cancer Staging Manual 8th Edition" from system http://ncithesaurus-stage.nci.nih.gov

When you run SUSHI against a project with rules like this, you get errors like this from SUSHI:

error Concept C146985 specifies system multiple times

[cmoesel]

This was OBE and no longer manifests in GoFSH.