Major Description
As reported in http://www.nabble.com/Not-able-to-back-up-to-S3-td16737029.html#a16737029, when the hostname in an S3 URI contains an underscore the exception reports a problem with S3 credentials. In the absence of URI complaining (see http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6587184) we can check that the host is non-null before checking user info (since URI.getHost returns null if the host contains an underscore).