Spoofax 3 Statix check broken on priorities that list the full rule

[Apanatshka]

Listing the full rule in a priorities section is allowed and even necessary when you want to talk about an injection like in the Stratego 2 syntax:

context-free priorities
  StrategoLang-Term.NoAnnoList = StrategoLang-PreTerm { } <0>. > {StrategoLang-PreTerm = StrategoLang-Var { }
                                                                  StrategoLang-PreTerm = StrategoLang-Wld { }}

But this is seen as a new definition of an existing constructor, which is incorrect.