fix it

Author: oconnor663

duct.py

@@ -558,7 +558,7 @@ def start_cmd(context, prog, args):
     # have to think carefully about the `close_fds` flag, and we wrapped child
     # spawning in a mutex. But as of Python 3.7, `subprocess` has safe defaults
     # for all of this. Progress!
-    return SharedChild(command, close_fds=False, **kwargs)
+    return SharedChild(command, **kwargs)
 
 
 def start_pipe(context, left_expr, right_expr):