Add selectors2

config/requirements.txt

@@ -43,6 +43,7 @@ pytest-mock
 pytz>=2015.7
 readline>=6.2.4
 requests>=2.9.1
+selectors2
 simplejson>=3.8.1
 six>=1.10
 # Freeze until all problems with 1.4 are solved

tests/integration/test_dyn_import.py

@@ -55,6 +55,7 @@
                    'PilotWrapper',  # in the pilot
                    'irods',  # not clear whether someone in DIRAC still uses it
                    'lfcthr',  # used by the LFC plugins
+                   'pathlib',  # only used for Python 3 installations
                    ]
 
 # List of modules that need graphic libraries.