asyncio: Close the transport on subprocess creation failure

Lib/asyncio/unix_events.py

@@ -177,7 +177,11 @@ class _UnixSelectorEventLoop(selector_events.BaseSelectorEventLoop):
             transp = _UnixSubprocessTransport(self, protocol, args, shell,
                                               stdin, stdout, stderr, bufsize,
                                               extra=extra, **kwargs)
-            yield from transp._post_init()
+            try:
+                yield from transp._post_init()
+            except:
+                transp.close()
+                raise
             watcher.add_child_handler(transp.get_pid(),
                                       self._child_watcher_callback, transp)
 

Lib/asyncio/windows_events.py

@@ -272,7 +272,12 @@ class ProactorEventLoop(proactor_events.BaseProactorEventLoop):
         transp = _WindowsSubprocessTransport(self, protocol, args, shell,
                                              stdin, stdout, stderr, bufsize,
                                              extra=extra, **kwargs)
-        yield from transp._post_init()
+        try:
+            yield from transp._post_init()
+        except:
+            transp.close()
+            raise
+
         return transp