Using the following command usually fails within an hour: while [ $? -eq 0 ]; do ./run-tests.py ./custom_cluster/test_breakpad.py --exploration_strategy=exhaustive -k test_minidump_relative_path -x -s; done. The problem is, that only two of the three impalad processes will write a minidump, while one of them won't. However in that case there is no breakpad related error message in its logfile.
Creating the minidump_base_dir seems to alleviate the problem, suggesting there might be a race condition somewhere in the call to boost::filesystem::create_directories.
This problem only seems to arise in the specific scenario of multiple impalad processes sharing the same minidump_base_dir which also has to be non-existent. Outside of tests it seems like it cannot occur.