Fix for uri replace whene uri has fragment. Was adding a second '#'.

sdk/lib/core/uri.dart

 // Copyright (c) 2012, 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.
 
 part of dart.core;
 
 // Frequently used character codes.
 const int _SPACE = 0x20;
 const int _PERCENT = 0x25;
 const int _PLUS = 0x2B;
@@ skipping 4189 matching lines @@
     if (query != null || queryParameters != null) {
       query = _Uri._makeQuery(
           query, 0, _stringOrNullLength(query), queryParameters);
     } else if (_queryStart < _fragmentStart) {
       query = _uri.substring(_queryStart, _fragmentStart);
     }
 
     if (fragment != null) {
       fragment = _Uri._makeFragment(fragment, 0, fragment.length);
     } else if (_fragmentStart < _uri.length) {
-      fragment = _uri.substring(_fragmentStart);
+      fragment = _uri.substring(_fragmentStart + 1);
     }
 
     return new _Uri._internal(
         scheme, userInfo, host, port, path, query, fragment);
   }
 
   Uri resolve(String reference) {
     return resolveUri(Uri.parse(reference));
   }
 
@@ skipping 235 matching lines @@
   int delta = (text.codeUnitAt(start + 4) ^ _COLON) * 3;
   delta |= text.codeUnitAt(start)     ^ 0x64 /*d*/;
   delta |= text.codeUnitAt(start + 1) ^ 0x61 /*a*/;
   delta |= text.codeUnitAt(start + 2) ^ 0x74 /*t*/;
   delta |= text.codeUnitAt(start + 3) ^ 0x61 /*a*/;
   return delta;
 }
 
 /// Helper function returning the length of a string, or `0` for `null`.
 int _stringOrNullLength(String s) => (s == null) ? 0 : s.length;