为什么我使用该dev_appserver.py选项运行时watcher_ignore_re，我收到一条错误消息，指出正则表达式is not JSON serializable.
这是开发服务器的错误吗？我这个命令使用不当吗？命令和调用堆栈打印如下。
C:\Users\mes65\Documents\MyProject>"C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\bin\dev_appserver.py" ^
--watcher_ignore_re="(.*\.git|.*\.idea|tmp\.py)" ^
"C:\Users\mes65\Documents\MyProject"
WARNING 2018-06-06 09:28:59,161 appinfo.py:1622] lxml version "2.3" is deprecated, use one of: "3.7.3"
INFO 2018-06-06 09:28:59,187 devappserver2.py:120] Skipping SDK update check.
Traceback (most recent call last):
File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\dev_appserver.py", line 96, in <module>
_run_file(__file__, globals())
File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\dev_appserver.py", line 90, in _run_file
execfile(_PATHS.script_file(script_name), globals_)
File "C:\Program Files (x86)\Google\Cloud SDK\google-cloud-sdk\platform\google_appengine\google\appengine\tools\devappserver2\devappserver2.py", line 454, in <module>
main()
File "C:\Program Files …