tor's test-network hangs when used with make -j2

(GNU) Make 3.81 has a bug/feature where if it is running processes in parallel using -j2 (or more), it waits until all descendent processes have exited before it returns to the shell.

When a command like "make -j2 test-network" is run, this means that test-network apparently hangs until it either make or all the tor processes have exited.

A workaround is to use make without -j, or make -j1 if there is an existing alias to "make -jn" in the shell.

One way to resolve this bug in tor is to use "chutney stop" after "chutney verify" in test-network.sh. I'll post a github branch that does this shortly.

Another, far more complex way would be to start another process group in chutney or something - but that would probably have unintended consequences.