--- a/config/mozunit/mozunit/mozunit.py
+++ b/config/mozunit/mozunit/mozunit.py
@@ -228,13 +228,12 @@ def main(*args, **kwargs):
     else:
         args = list(args)
         if os.environ.get('MACH_STDOUT_ISATTY') and not any(a.startswith('--color') for a in args):
             args.append('--color=yes')
 
         module = __import__('__main__')
         args.extend([
             '-vv',
-            '-p', 'mozlog.pytest_mozlog.plugin',
             '-p', 'no:cacheprovider',
             module.__file__,
         ])
         sys.exit(pytest.main(args))

--- a/python/mach_commands.py
+++ b/python/mach_commands.py
@@ -94,21 +94,18 @@ class MachCommands(MachCommandBase):
     def run_python_tests(self,
                          tests=None,
                          test_objects=None,
                          subsuite=None,
                          verbose=False,
                          jobs=1,
                          three=False,
                          **kwargs):
-        if three:
-            # use pipenv to run tests against Python 3
-            self.activate_pipenv(os.path.join(here, 'Pipfile'), ['--three'])
-        else:
-            self._activate_virtualenv()
+        pipenv_args = ['--three' if three else '--two']
+        self.activate_pipenv(os.path.join(here, 'Pipfile'), pipenv_args)
 
         if test_objects is None:
             from moztest.resolve import TestResolver
             resolver = self._spawn(TestResolver)
             # If we were given test paths, try to find tests matching them.
             test_objects = resolver.resolve_tests(paths=tests, flavor='python')
         else:
             # We've received test_objects from |mach test|. We need to ignore