NB: It does not reproduce the issue yet and I'm hoping you can help modify until it does. One thing I will point out that is fishy about your output is:

...
00:12:29.917 [services unit tests - python]                          self.result = func()
...

Neither Pants 1.4.0, nor any version I know of, prefixes log lines with

[services unit tests - python]

. @bulky-library-34172 can you first confirm your Pants installation is customized? If so, can you provide details of how it is customized? If not, can you explain the abnormal log line prefixes? For example, the full output of the minimal repro repo linked above looks like:

$ ./pants test tests/::
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100   122  100   122    0     0    237      0 --:--:-- --:--:-- --:--:--   236
100   281  100   281    0     0    288      0 --:--:-- --:--:-- --:--:--   288
  0     0    0     0    0     0      0      0 --:--:--  0:00:01 --:--:--     0
100 2576k  100 2576k    0     0  1101k      0  0:00:02  0:00:02 --:--:-- 6925k
New python executable in /home/jsirois/.cache/pants/setup/bootstrap-Linux-x86_64/pants.c1peuM/install/bin/python2.7
...
08:37:55 00:02   [pyprep]
08:37:55 00:02     [interpreter]
08:38:04 00:11     [requirements]
08:38:04 00:11     [sources]
08:38:04 00:11       [cache] 
                   No cached artifacts for 1 target.
                   Invalidated 1 target.
08:38:04 00:11   [compile]
08:38:04 00:11     [compile-jvm-prep-command]
08:38:04 00:11       [jvm_prep_command]
08:38:04 00:11     [compile-prep-command]
08:38:04 00:11     [compile]
08:38:04 00:11     [zinc]
08:38:04 00:11     [jvm-dep-check]
08:38:04 00:11   [test]
08:38:04 00:11     [test-jvm-prep-command]
08:38:04 00:11       [jvm_prep_command]
08:38:04 00:11     [test-prep-command]
08:38:04 00:11     [test]
08:38:04 00:11     [pytest-prep]
08:38:04 00:11       [cache] 
                   No cached artifacts for 1 target.
                   Invalidated 1 target.
08:38:04 00:11       [cache] 
                   No cached artifacts for 1 target.
                   Invalidated 1 target.
08:38:22 00:29     [pytest]
08:38:22 00:29       [cache] 
                   No cached artifacts for 1 target.
                   Invalidated 1 target.
08:38:22 00:29       [run]
                     ============== test session starts ===============
                     platform linux2 -- Python 2.7.15, pytest-3.7.0, py-1.5.4, pluggy-0.7.1
                     rootdir: /tmp/pants1.4, inifile:
                     plugins: cov-2.4.0, timeout-1.2.1
                     collected 2 items
                     
                     tests/python/example/test_packages.py ..   [100%]
                     
                      generated xml file: /tmp/pants1.4/.pants.d/test/pytest/tests.python.example.example/junitxml/TEST-tests.python.example.example.xml 
                     ============ 2 passed in 0.01 seconds ============
                     
                   tests/python/example                                                            .....   SUCCESS
08:38:22 00:29     [junit]WARN] /home/jsirois/.cache/pants/setup/bootstrap-Linux-x86_64/1.4.0/lib/python2.7/site-packages/pants/backend/jvm/tasks/junit_run.py:759: DeprecationWarning: DEPRECATED: [test.junit] legacy_report_layout will be removed in version 1.6.0.dev0.
  Reports are now linked into /tmp/pants1.4/dist/test/junit by default; so scripts and CI jobs should be pointed there and the option configured to False in pants.ini until such time as the option is removed.
  'the option is removed.'.format(dist_dir))


               Waiting for background workers to finish.
08:38:22 00:29   [complete]
               SUCCESS