add _load_params debug overrides for module args/file passed on cmdline

Updated python module wrapper explode method to drop 'args' file next to module.
Both execute() and excommunicate() debug methods now pass the module args via file to enable debuggers that are picky about stdin.
Updated unit tests to use a context manager for masking/restoring default streams and argv.

test/units/module_utils/test_distribution_version.py

@@ -26,6 +26,8 @@ from io import BytesIO, StringIO
 from ansible.compat.six import PY3
 from ansible.utils.unicode import to_bytes
 
+from units.mock.procenv import swap_stdin_and_argv
+
 # for testing
 from ansible.compat.tests import unittest
 from ansible.compat.tests.mock import patch
@@ -323,26 +325,17 @@ def test_distribution_version():
     # needs to be in here, because the import fails with python3 still
     import ansible.module_utils.facts as facts
 
-    real_stdin = sys.stdin
     from ansible.module_utils import basic
 
     args = json.dumps(dict(ANSIBLE_MODULE_ARGS={}, ANSIBLE_MODULE_CONSTANTS={}))
-    if PY3:
-        sys.stdin = StringIO(args)
-        sys.stdin.buffer = BytesIO(to_bytes(args))
-    else:
-        sys.stdin = BytesIO(to_bytes(args))
-    module = basic.AnsibleModule(argument_spec=dict())
-
-    for t in TESTSETS:
-        # run individual tests via generator
-        # set nicer stdout output for nosetest
-        _test_one_distribution.description = "check distribution_version for %s" % t['name']
-        yield _test_one_distribution, facts, module, t
-
-
-    sys.stdin = real_stdin
+    with swap_stdin_and_argv(stdin_data=args):
+        module = basic.AnsibleModule(argument_spec=dict())
 
+        for t in TESTSETS:
+            # run individual tests via generator
+            # set nicer stdout output for nosetest
+            _test_one_distribution.description = "check distribution_version for %s" % t['name']
+            yield _test_one_distribution, facts, module, t
 
 def _test_one_distribution(facts, module, testcase):
     """run the test on one distribution testcase