Revert "use gemfile over settings (not tested yet)"

It turns out that we already use Gemfile auth over configured auth,
because the Gemfile URI includes the username and password. That means
that mirrors and configured auth will not be used for any URI with auth
in it.

This reverts commit 88969b5.

lib/bundler/fetcher.rb

@@ -379,12 +379,10 @@ def resolve_remote_uri(uri)
 
     def add_configured_credentials(uri)
       auth = Bundler.settings[uri.to_s]
-
-      if auth && uri.user.nil?
+      if auth
         uri = uri.dup
         uri.user, uri.password = *auth.split(":", 2)
       end
-
       AnonymizableURI.new(uri)
     end