The code in LobStreamsTest that failed, looks like this:
InputStream lStream = rs3.getClob(1).getAsciiStream();
assertTrue("FAIL - Clob and file contents do not match",
I think the problem is that the Clob object is garbage collected before the stream has been exhausted, and EmbedClob.finalize() closes the container. I think this affects earlier releases as well, but I'm only marking it as a 10.3 issue for now since I haven't verified it.