diff --git a/test/runner/lib/delegation.py b/test/runner/lib/delegation.py
index a5de0e0332f..0a63754defa 100644
--- a/test/runner/lib/delegation.py
+++ b/test/runner/lib/delegation.py
@@ -16,6 +16,7 @@ from lib.executor import (
     SubprocessError,
     ShellConfig,
     SanityConfig,
+    UnitsConfig,
     create_shell_command,
 )
 
@@ -201,6 +202,10 @@ def delegate_docker(args, exclude, require):
         docker_exec(args, test_id, ['mkdir', '/root/ansible'])
         docker_exec(args, test_id, ['tar', 'oxzf', '/root/ansible.tgz', '-C', '/root/ansible'])
 
+        # docker images are only expected to have a single python version available
+        if isinstance(args, UnitsConfig) and not args.python:
+            cmd += ['--python', 'default']
+
         try:
             docker_exec(args, test_id, cmd, options=cmd_options)
         finally:
@@ -356,6 +361,10 @@ def delegate_remote(args, exclude, require):
             if not args.allow_destructive:
                 cmd.append('--allow-destructive')
 
+        # remote instances are only expected to have a single python version available
+        if isinstance(args, UnitsConfig) and not args.python:
+            cmd += ['--python', 'default']
+
         manage = ManagePosixCI(core_ci)
         manage.setup()
 
diff --git a/test/runner/lib/util.py b/test/runner/lib/util.py
index 3607268e34a..74942d4b573 100644
--- a/test/runner/lib/util.py
+++ b/test/runner/lib/util.py
@@ -477,6 +477,9 @@ class EnvironmentConfig(CommonConfig):
 
         self.requirements = args.requirements  # type: bool
 
+        if self.python == 'default':
+            self.python = '.'.join(str(i) for i in sys.version_info[:2])
+
         self.python_version = self.python or '.'.join(str(i) for i in sys.version_info[:2])
 
         self.delegate = self.tox or self.docker or self.remote
diff --git a/test/runner/requirements/units.txt b/test/runner/requirements/units.txt
index 085c9ab63c0..26bcd641b25 100644
--- a/test/runner/requirements/units.txt
+++ b/test/runner/requirements/units.txt
@@ -12,5 +12,6 @@ pytest-xdist
 python-memcached
 pyyaml
 redis
+setuptools > 0.6 # pytest-xdist installed via requirements does not work with very old setuptools (sanity_ok)
 unittest2 ; python_version < '2.7'
 netaddr
diff --git a/test/runner/test.py b/test/runner/test.py
index 56fc4a76621..801f07f9634 100755
--- a/test/runner/test.py
+++ b/test/runner/test.py
@@ -241,7 +241,7 @@ def parse_args():
 
     units.add_argument('--python',
                        metavar='VERSION',
-                       choices=SUPPORTED_PYTHON_VERSIONS,
+                       choices=SUPPORTED_PYTHON_VERSIONS + ('default',),
                        help='python version: %s' % ', '.join(SUPPORTED_PYTHON_VERSIONS))
 
     units.add_argument('--collect-only',
diff --git a/test/sanity/code-smell/test-constraints.sh b/test/sanity/code-smell/test-constraints.sh
index 0bbaad53b07..773306c4d0a 100755
--- a/test/sanity/code-smell/test-constraints.sh
+++ b/test/sanity/code-smell/test-constraints.sh
@@ -2,6 +2,7 @@
 
 constraints=$(
     grep '.' test/runner/requirements/*.txt \
+        | grep -v '(sanity_ok)$' \
         | sed 's/ *;.*$//; s/ #.*$//' \
         | grep -v '/constraints.txt:' \
         | grep '[<>=]'
diff --git a/test/units/conftest.py b/test/units/conftest.py
index 387fa77b87f..2cd1f74596b 100644
--- a/test/units/conftest.py
+++ b/test/units/conftest.py
@@ -7,6 +7,11 @@ try:
 except ImportError:
     coverage = None
 
+try:
+    test = coverage.Coverage
+except AttributeError:
+    coverage = None
+
 
 def pytest_configure():
     if not coverage: