diff -r d0ed9643cd57 Lib/subprocess.py
--- a/Lib/subprocess.py	Thu Nov 17 23:31:29 2016 -0600
+++ b/Lib/subprocess.py	Fri Nov 18 03:50:20 2016 -0800
@@ -1031,6 +1031,9 @@
             """Wait for child process to terminate.  Returns returncode
             attribute."""
             if endtime is not None:
+                warnings.warn(
+                    "'endtime' argument is deprecated. Use 'timeout' instead",
+                    DeprecationWarning)
                 timeout = self._remaining_time(endtime)
             if timeout is None:
                 timeout_millis = _winapi.INFINITE