I have encountered the same problem while doing the groovy pre-release 
test of ethzasl_message_transport. My understanding is that the 
pre-release farm is running on an old cluster and is in a somewhat shaky 
state. I have also encountered funny errors like "Too many open files" 
and others, clearly not linked to my stack.

I unfortunately have no useful advise on how to work-around this 
problem, I can just say that you are not alone.

Kind regards,

Stéphane

-- 
Dr Stéphane Magnenat
http://stephane.magnenat.net