Add python.py coverage injector for ansible-test.

This can be used to run Python scripts from the repository with the
correct interpreter and allow collection of code coverage.

Useful for testing contrib inventory scripts.

(cherry picked from commit 45b5685037)

test/runner/injector/injector.py

@@ -110,6 +110,8 @@ def main():
                 args, env, require_cwd = cover()
             else:
                 args, env = runner()
+        elif os.path.basename(__file__) == 'python.py':
+            args, env = python()  # run arbitrary python commands using the correct python and with optional code coverage
         else:
             args, env = injector()
 
@@ -142,6 +144,20 @@ def main():
         raise
 
 
+def python():
+    """
+    :rtype: list[str], dict[str, str]
+    """
+    if config.coverage_file:
+        args, env = coverage_command()
+    else:
+        args, env = [config.python_interpreter], os.environ.copy()
+
+    args += config.arguments[1:]
+
+    return args, env
+
+
 def injector():
     """
     :rtype: list[str], dict[str, str]

test/runner/injector/python.py

@@ -0,0 +1 @@
+injector.py