PHP Google App Engine Charset UTF无法正常工作

I'm using google app engine for a php based web app. The content type is set in the html header as following.

<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">

Whenever I submit a html code sample from a form(Which is having a image upload field also), and that html code is converted into html entities like below,

htmlentities(stripslashes($_POST['code']), ENT_QUOTES, "UTF-8" );

There are some strange characters in the output like "=3D" for any "=" characters in the the code. I believe this is due to some error in the charset I'm working with.

This piece of code works fine in my localhost fine.

I tried following the solutions given in Defining CharSet for static HTML files , but the problem is my app.yml does not include only html files, it has other formats also. The app.yml looks like this.

- url: /(.*\.(ico$|jpg$|png$|gif$|htm$|html$|css$|js$|vtt$|swf$|woff$|ttf$))
  static_files: \1
  upload: (.*\.(ico$|jpg$|png$|gif$|htm$|html$|css$|js$|mp3$|flv$|vtt$|swf$|woff$|ttf$))
  application_readable: true

Is this actually due to some character encoding issue? How can I overcome this?

Thanks & Regards!

I think you're hitting this known issue. If it is, then you should star the issue if you can.