Isolate Concurrency errors in dedicated appender

Since we have ITRichFileuploadTest which systematically causes NXP-12865 i.e.

Caused by: java.lang.IllegalStateException: Concurrency Error: Session was started in thread 86 (http-bio-0.0.0.0-8080-exec-19) but is being used in thread 91 (http-bio-0.0.0.0-8080-exec-24)

the following job is always unstable:

• http://qa.nuxeo.org/jenkins/job/FT-nuxeo-master-webdriver-dm-tomcat

As a result, the dowstream jobs are never launched:

• FT-nuxeo-master-webdriver-dm-tomcat-multiosdb last build Mar 13, 2014 1:47:51 PM
• FT-nuxeo-master-webdriver-dm-tomcat-win last buid Mar 11, 2014 1:59:28 PM

I believe this is a big issue because we won't figure out that we broke something on these environments.

Here are the options I believe we have:

• Configure these jobs to launch their dowstream jobs even when unstable (but Julien does not like it)
• Disable ITRichfileuploadTest (but I don't like it)
• Stephane suggested to configure log4j to logs concurrency errors in a different appender that won't be scanned by Jenkins. If needed we could throw a more specific Exception than IllegalStateException to achieve this.