Ignore renamed formulae when checking for unversioned formulae

There is an audit for versioned formulae that makes sure
an unversioned formulae of the same name exists already.
This ignores that check when we exlicitly removed the
unversioned formula by checking if it was renamed.

Also, there is no need to check for formula.tap because
formula.core_formula? guarantees the presence of formula.tap.

Library/Homebrew/formula_auditor.rb

@@ -52,14 +52,16 @@ module Homebrew
 
     def audit_file
       if formula.core_formula? && @versioned_formula
+        unversioned_name = formula.name.gsub(/@.*$/, "")
+
+        # ignore when an unversioned formula doesn't exist after an explicit rename
+        return if formula.tap.formula_renames.key?(unversioned_name)
+
+        # build this ourselves as we want e.g. homebrew/core to be present
+        full_name = "#{formula.tap}/#{unversioned_name}"
+
         unversioned_formula = begin
-          # build this ourselves as we want e.g. homebrew/core to be present
+          Formulary.factory(full_name).path
-          full_name = if formula.tap
-            "#{formula.tap}/#{formula.name}"
-          else
-            formula.name
-          end
-          Formulary.factory(full_name.gsub(/@.*$/, "")).path
         rescue FormulaUnavailableError, TapFormulaAmbiguityError,
                TapFormulaWithOldnameAmbiguityError
           Pathname.new formula.path.to_s.gsub(/@.*\.rb$/, ".rb")