issue #477: target.file_exists() wrapper.

os.path.exists physical module name varies across major Python versions.

ansible_mitogen/mixins.py

@@ -155,7 +155,7 @@ class ActionModuleMixin(ansible.plugins.action.ActionBase):
         """
         LOG.debug('_remote_file_exists(%r)', path)
         return self._connection.get_chain().call(
-            os.path.exists,
+            ansible_mitogen.target.file_exists,
             mitogen.utils.cast(path)
         )
 

ansible_mitogen/target.py

@@ -752,3 +752,12 @@ def set_file_mode(path, spec, fd=None):
         os.fchmod(fd, new_mode)
     else:
         os.chmod(path, new_mode)
+
+
+def file_exists(path):
+    """
+    Return :data:`True` if `path` exists. This is a wrapper function over
+    :func:`os.path.exists`, since its implementation module varies across
+    Python versions.
+    """
+    return os.path.exists(path)