diff -r 9fb9f8440b71 -r 765eb17a7eb8 mercurial/thirdparty/attr/_config.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mercurial/thirdparty/attr/_config.py	Sun Oct 01 04:14:16 2017 -0700
@@ -0,0 +1,23 @@
+from __future__ import absolute_import, division, print_function
+
+
+__all__ = ["set_run_validators", "get_run_validators"]
+
+_run_validators = True
+
+
+def set_run_validators(run):
+    """
+    Set whether or not validators are run.  By default, they are run.
+    """
+    if not isinstance(run, bool):
+        raise TypeError("'run' must be bool.")
+    global _run_validators
+    _run_validators = run
+
+
+def get_run_validators():
+    """
+    Return whether or not validators are run.
+    """
+    return _run_validators