[Android] FAIL src/test/test_process_slow.c:240: assert(smartlist_len(process_data->stdout_data) OP_EQ 12): 2 vs 12

Running the test-slow suite fails every time with this error on 0.4.1.x, 0.4.2.x, and master:

slow/process/callbacks: 
  FAIL src/test/test_process_slow.c:240: assert(smartlist_len(process_data->stdout_data) OP_EQ 12): 2 vs 12
  [callbacks FAILED]

The full build/test log is here: https://gitlab.com/eighthave/tor/-/jobs/336701282

To try this yourself, it'll be easiest using the Guardian Project fork, which is in sync on GitHub and GitLab:

• https://github.com/guardianproject/tor
• https://gitlab.com/guardianproject/tor

I looked into it a bit, but couldn't quite figure out what was being tested there. Is it Tor's "smartlist" functions? stdin/stdout/stderr have annoying, arbitrary restrictions in Android, so it could be related to that. For example, "native" code loaded from a shared library will have stdin/stdout/stderr redirected to /dev/null, while in Java code, it is reachable. There is a related example on legacy/trac#32036 (moved)