partial fix for issue circus-tent#979

avoir the main and blocking exception about "I/O operation on closed file"
with minimal changes and risks

circus/stream/redirector.py

@@ -44,8 +44,7 @@ def __init__(self, stdout_redirect, stderr_redirect, buffer=1024,
  self.buffer = buffer
  self.loop = loop or ioloop.IOLoop.instance()
 
- def _start_one(self, stream_name, process, pipe):
- fd = pipe.fileno()
+ def _start_one(self, fd, stream_name, process, pipe):
  if fd not in self._active:
  handler = self.Handler(self, stream_name, process, pipe)
  self.loop.add_handler(fd, handler, ioloop.IOLoop.READ)
@@ -55,8 +54,9 @@ def _start_one(self, stream_name, process, pipe):
 
  def start(self):
  count = 0
- for name, process, pipe in self.pipes.values():
- count += self._start_one(name, process, pipe)
+ for fd, value in self.pipes.items():
+ name, process, pipe = value
+ count += self._start_one(fd, name, process, pipe)
  self.running = True
  return count
 
@@ -87,7 +87,7 @@ def add_redirections(self, process):
  self._stop_one(fd)
  self.pipes[fd] = name, process, pipe
  if self.running:
- self._start_one(name, process, pipe)
+ self._start_one(fd, name, process, pipe)
  process.redirected = True
 
  def remove_fd(self, fd):