I can't remember this happened before with a probability of 1.4%:
$ for i in {0..1000}; do ./qa/pull-tester/rpc-tests.py disablewallet; echo $? >> /tmp/e; done; cat /tmp/e|sort|uniq -c;
989 0
14 1
Error: Unable to start HTTP server. See debug log for details.
bitcoind: /usr/include/boost/thread/pthread/condition_variable_fwd.hpp:81: boost::condition_variable::~condition_variable(): Assertion `!ret' failed.
error: incorrect rpcuser or rpcpassword (authorization failed)
Error: Unable to start HTTP server. See debug log for details.
bitcoind: scheduler.cpp:19: CScheduler::~CScheduler(): Assertion `nThreadsServicingQueue == 0' failed.
Error: Unable to start HTTP server. See debug log for details.
bitcoind: scheduler.cpp:19: CScheduler::~CScheduler(): Assertion `nThreadsServicingQueue == 0' failed.
error: incorrect rpcuser or rpcpassword (authorization failed)