errpipe_read must be non-blocking

Author: Martiusweb

asyncio/unix_events.py

@@ -664,6 +664,7 @@ def _cleanup_on_exec_failure(self):
 
     def _get_exec_err_pipe(self):
         errpipe_read, errpipe_write = self._loop._socketpair()
+        errpipe_read.setblocking(False)
         _set_inheritable(errpipe_write.fileno(), False)
         return errpipe_read.detach(), errpipe_write.detach()