When one follows the instructions located in README.md for H2O module and tries to run tests in the distributed mode, tests run only in the local mode. There are three steps in the instruction:
First two steps are for executing worker nodes. The last one is for executing tests. According to the instruction, after launching tests one more worker is started. And it should join to the same cloud which other worker nodes forms. But it does joined them because it has a different cloud name (or masterURL in terms of the code). If you look in the code, you can find the following:
After we removed the code which appends current time to cloud name, it started to work.