I agree that test_crashed() should be skipped on Android anyway and I will create a PR to skip the test.

If I understand correctly, there may be another nasty bug that is revealed when test_regrstest fails with the environment altered:

    How is it possible that the new file that alters the environment be a test_python_* directory (see my initial post) when all the tests are run inside a TEMPDIR/test_python_* directory. The 'files' environment is checked within a TEMPDIR/test_python_* and not within TEMPDIR, no ?

I found a new point that may help understand this problem:

* On Android TEMPDIR is built from tempfile.gettempdir() that uses the TMPDIR environment variable which is set by Android to /data/local/tmp. The tests are run in /data/local/tmp/python [1], this is also the value of $SYS_EXEC_PREFIX and thus where are installed Python machine-specific binaries.

* When TMPDIR is set to /data/local/tmp/python/tmp, which makes more sense here, test_regrstest is ok and does not change the environment.

[1] This is the only location where a shell user may have both write and exec permissions, the Android applications have those permissions here too and in their own dedicated locations on /data/data.