We don't need even a token timeout here; just poll once

The process is already gone, so there's not going to be any new data
showing up on its stderr; we only want to make sure that we haven't
missed something that was already written. So polling once is enough.

lib/ansible/plugins/connection/ssh.py

@@ -542,11 +542,13 @@ class Connection(ConnectionBase):
                 # When ssh has ControlMaster (+ControlPath/Persist) enabled, the
                 # first connection goes into the background and we never see EOF
                 # on stderr. If we see EOF on stdout and the process has exited,
-                # we're done. Just to be extra sure that we aren't missing any
-                # output on stderr, we call select again with a small timeout.
+                # we're probably done. We call select again with a zero timeout,
+                # just to make certain we don't miss anything that may have been
+                # written to stderr between the time we called select() and when
+                # we learned that the process had finished.
 
                 if not p.stdout in rpipes:
-                    timeout = 0.001
+                    timeout = 0
                     continue
 
             # If the process has not yet exited, but we've already read EOF from