audit: fix full versioned alias name resolution in taps

This fixes an issue where audit would prompt for the creation
of an already existing versioned alias while at the same time
declaring the existing alias invalid.

Library/Homebrew/dev-cmd/audit.rb

@@ -323,6 +323,10 @@ class FormulaAuditor
       end
       valid_alias_names = [alias_name_major, alias_name_major_minor]
 
+      if formula.tap
+        valid_alias_names.map! { |a| "#{formula.tap}/#{a}" }
+      end
+
       valid_versioned_aliases = versioned_aliases & valid_alias_names
       invalid_versioned_aliases = versioned_aliases - valid_alias_names