Travis CI: Run each failing pytest in ; || true mode

Author: cclauss

.travis.yml

@@ -21,14 +21,14 @@ script:
       --ignore=machine_learning/random_forest_regression/random_forest_regression.py
   # The following files currently fail pytests.  See issues: #1016, #1044, #1080
   # Here they are run || true and when each passes pytest, it can be removed above and below.
-  - pytest data_structures/stacks/balanced_parentheses.py --doctest-modules || true
-  - pytest data_structures/stacks/infix_to_postfix_conversion.py --doctest-modules || true
-  - pytest file_transfer_protocol/ftp_send_receive.py --doctest-modules || true
+  - pytest data_structures/stacks/balanced_parentheses.py --doctest-modules ; || true
+  - pytest data_structures/stacks/infix_to_postfix_conversion.py --doctest-modules ; || true
+  - pytest file_transfer_protocol/ftp_send_receive.py --doctest-modules ; || true
   # ftp_client_server.py currently hangs until Travis CI times out (10+ minutes)
-  # - pytest file_transfer_protocol/ftp_client_server.py --doctest-modules || true
-  - pytest machine_learning/linear_regression.py --doctest-modules || true
-  - pytest machine_learning/random_forest_classification/random_forest_classification.py --doctest-modules || true
-  - pytest machine_learning/random_forest_regression/random_forest_regression.py --doctest-modules || true
+  # - pytest file_transfer_protocol/ftp_client_server.py --doctest-modules ; || true
+  - pytest machine_learning/linear_regression.py --doctest-modules ; || true
+  - pytest machine_learning/random_forest_classification/random_forest_classification.py --doctest-modules ; || true
+  - pytest machine_learning/random_forest_regression/random_forest_regression.py --doctest-modules ; || true
 
 after_success:
   - scripts/build_directory_md.py > DIRECTORY.md