Ensure that returned cached source have the same actual URI.

pkg/analyzer/lib/src/context/source.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library analyzer.src.context.source;
 
 import 'dart:collection';
 import 'dart:math' show min;
 
 import 'package:analyzer/exception/exception.dart';
@@ skipping 238 matching lines @@
 
       if (packageUri != null) {
         // Ensure scheme is set.
         if (packageUri.scheme == '') {
           packageUri = packageUri.replace(scheme: 'file');
         }
         containedUri = packageUri;
       }
     }
 
-    return _absoluteUriToSourceCache.putIfAbsent(containedUri, () {
+    return _absoluteUriToSourceCache.putIfAbsent(actualUri, () {
       for (UriResolver resolver in resolvers) {
         Source result = resolver.resolveAbsolute(containedUri, actualUri);
         if (result != null) {
           return result;
         }
       }
       return null;
     });
   }
 }