In WT-4486, a test case is clearly failing (giving a Python stack trace), but the results.txt file has: passed=True and the directory is removed.  This behavior occurs with the -j option, and does not occur without that.

To reproduce in the same way as in WT-4486, one needs to change test_log03.py to alter the line in test_dirty_max to be:

  for dirty_pct,increase in [[50, 50]]:

Then run:

$ cd build_posix
$ env LD_LIBRARY_PATH=.libs:lang/python python ../test/suite/run.py -v 2 -j 4 log 

This was noticed on a non-zseries linux box, but it is the same on regular linux.