appEngine nginx not able to redirect to index.html when the url contains "-" dash

[fenglin]

forget about this, after investigation, I discover it is related with some
angular "-" in the url parameter problem. 
angular does not allow "-" in url route parameter, it will cause 404 error.

but it does not clearly say the value of the parameter contains problem, and
if we add a extra postfix, the problem can be walk around.
it is not related with nginx.

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,285897,285902#msg-285902