Don't Throw Error when setting unittest config twice

pkg/unittest/lib/unittest.dart

Index: pkg/unittest/lib/unittest.dart
===================================================================
--- pkg/unittest/lib/unittest.dart	(revision 42037)
+++ pkg/unittest/lib/unittest.dart	(working copy)
@@ -194,7 +194,9 @@
 void set unittestConfiguration(Configuration value) {
   if (!identical(_config, value)) {
     if (_config != null) {
-      throw new StateError('unittestConfiguration has already been set');
+      logMessage('Warning: The unittestConfiguration has already been set. New '
+          + 'unittestConfiguration ignored.');

[kevmoo, 2014/12/08 21:04:46]

Remove '+' adjacent string literals automatically concat.

[Nicolas Garnier, 2014/12/08 21:18:15]

Done.

+      return;

[kevmoo, 2014/12/08 21:04:45]

Use an else block instead of the in-block return

[Nicolas Garnier, 2014/12/08 21:18:15]

Done.

     }
     _config = value;
   }