Fixes issue #15756: subprocess.poll() now properly handles errno.ECHILD

to return a returncode of 0 when the child has already exited or cannot
be waited on.

1 files changed, 8 insertions, 1 deletions

diff --git a/Lib/subprocess.py b/Lib/subprocess.py
index 106af8b..93262df 100644
--- a/Lib/subprocess.py
+++ b/Lib/subprocess.py
@@ -1400,9 +1400,16 @@ class Popen(object):
                     pid, sts = _waitpid(self.pid, _WNOHANG)
                     if pid == self.pid:
                         self._handle_exitstatus(sts)
-                except _os_error:
+                except _os_error as e:
                     if _deadstate is not None:
                         self.returncode = _deadstate
+                    elif e.errno == errno.ECHILD:
+                        # This happens if SIGCLD is set to be ignored or
+                        # waiting for child processes has otherwise been
+                        # disabled for our process.  This child is dead, we
+                        # can't get the status.
+                        # http://bugs.python.org/issue15756
+                        self.returncode = 0
             return self.returncode