unit test test_father fails with python2

[morxa]

The unit test test_father fails:

$ cd test
$ ./runtests
............F....
======================================================================
FAIL: test_father (test_examples.TestExamples)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "test_examples.py", line 137, in test_father
    self.assertEqual(len(result), 1)
AssertionError: 4 != 1

----------------------------------------------------------------------
Ran 17 tests in 5.313s

FAILED (failures=1)

When looking at the result, it contains the same result four times:

[{'Y': 'mich', 'Z': 'jane'}, {'Y': 'mich', 'Z': 'jane'}, {'Y': 'mich', 'Z': 'jane'}, {'Y': 'mich', 'Z': 'jane'}]

This is with commit 72771d9 and SWI-Prolog 7.2.3 on Fedora 25.

[morxa]

This occurs only when using Python2, runtests3 works as expected:

$ ./runtests3
.................
----------------------------------------------------------------------
Ran 17 tests in 5.383s

OK

[yuce]

This is fixed on master branch.