mono/mono — pull request #1079 by esdrubal (2014-06-02 18:22:19+00:00)
Title: UploadStringAsync cancel

**Problem**: UploadStringAsync not triggering UploadStringCompleted on cancellation.
**Cause**: Exceptions thrown by UploadString are encapsulated into a WebException.
**Fix**: Check if caught exception's InnerException is ThreadInterruptedException.