Unit tests leave stale directories behind #947
Description
$ ./test_reframe.py
============================================================================================= test session starts ==============================================================================================
platform linux -- Python 3.6.8, pytest-4.4.0, py-1.8.0, pluggy-0.13.0
rootdir: /users/karakasv/Devel/reframe
plugins: xdist-1.28.0, forked-1.0.2, cov-2.6.1, pep8-1.0.6, html-1.20.0, metadata-1.8.0
collected 585 items
unittests/test_argparser.py .. [ 0%]
unittests/test_buildsystems.py ........... [ 2%]
unittests/test_check_filters.py ........ [ 3%]
unittests/test_cli.py ....s...................... [ 8%]
unittests/test_color.py .. [ 8%]
unittests/test_config.py ............... [ 11%]
unittests/test_containers.py .... [ 11%]
unittests/test_deferrable.py .............................................. [ 19%]
unittests/test_environments.py sssssss.....s...... [ 22%]
unittests/test_exceptions.py ............. [ 25%]
unittests/test_fields.py ......... [ 26%]
unittests/test_launchers.py .............. [ 29%]
unittests/test_loader.py .......... [ 30%]
unittests/test_logging.py ............................... [ 36%]
unittests/test_modules.py ........ssssssssssssssss.............................. [ 45%]
unittests/test_pipeline.py ....s...s................................. [ 52%]
unittests/test_policies.py ............................................ [ 60%]
unittests/test_runtime.py . [ 60%]
unittests/test_sanity_functions.py ............................................................... [ 70%]
unittests/test_schedulers.py ............s...s......sss.s...s......sss.s...s...ss................................... [ 85%]
unittests/test_shell.py ...... [ 86%]
unittests/test_typecheck.py ........ [ 88%]
unittests/test_utility.py .................................................................. [ 99%]
unittests/test_versioning.py ... [100%]
=================================================================================== 544 passed, 41 skipped in 69.56 seconds ====================================================================================
[14:38:37] karakasv@dom101 [~/Devel/reframe][master]
$ ls unittests/tmp
tmp2c5qwaz3/ tmp5azhp5wo/ tmp7mzimts3/ tmp9ds5mxd8/ tmpgxnj3s6u/ tmpkzfy0v1z/ tmpnmnd81i0/ tmppv380sib/ tmpqv8j9qi8/ tmpyak_fsug/
tmp3a_9g5rx/ tmp5jzk3p1e/ tmp7pcre8as/ tmpfhxfbf3z/ tmpie3qjr14/ tmpn8t61toq/ tmpnyve95tx/ tmpqnob6onr/ tmpwy51rome/