test: quickly close pipes

tests/test_nginx.py

@@ -98,7 +98,7 @@ def {APP_FUNC_NAME}(environ, start_response):
         ("Content-Length", "%d" % len(body)),
     ]
     start_response("200 OK", response_head)
-    time.sleep(0.1)
+    time.sleep(0.02)
     return iter([body])
 """
 
@@ -204,6 +204,7 @@ def run(self):
             bufsize=0,  # allow read to return short
             cwd=self.temp_path,
             shell=False,
+            close_fds=True,
             stdin=subprocess.DEVNULL,
             stdout=subprocess.PIPE,
             stderr=subprocess.PIPE,
@@ -228,6 +229,8 @@ def graceful_quit(self, expect=None):
         except subprocess.TimeoutExpired:
             pass
         assert stdout == b""
+        self.p.stdout.close()
+        self.p.stderr.close()
         exitcode = self.p.poll()  # will return None if running
         assert exitcode == 0, (exitcode, stdout, stderr)
         print("output after signal: ", stdout, stderr, exitcode)