Fix error when importing a GitHub-wiki repository

This would occur when Wiki's are enabled on GitHub, but there is no
wiki repository

lib/github/import.rb

@@ -107,7 +107,7 @@ module Github
       # this means that repo has wiki enabled, but have no pages. So,
       # we can skip the import.
       if e.message !~ /repository not exported/
-        errors(:wiki, wiki_url, e.message)
+        error(:wiki, wiki_url, e.message)
       end
     end