Weird fail of "two labels" assertion when a concept is its own super-concept 👽

[matuskalas]

(editted, sorry I haven't seen properly at first)

@hmenager
There was a correct ...is superclass of itself error message and the correct the class has two labels, which is forbidden in EDAM message, but:

• it had some weird things printed out around the assertion of the "two labels"
• ideally, the "two labels" should perhaps return an error message about "multiple" labels, not specifically just 2
  
  It is here:
  https://travis-ci.org/github/edamontology/edamontology/builds/769727535

Not urgent, but would be nice to fix for perfection.