Zero-width space entity gets doubled

[Jakub Ś]

1. Set below in config.js

   config.entities = true;
   config.entities_processNumerical = true;
   

2. Go to editor, switch to source and paste below

   aaaaaa​​bbbbbbbbbbbbbb​​ccccccccccccccccccccc​​ddddddddddddddddd​​eeeeeeeeeeeeeeeeeeeeeeeeee​​fffffffffffffffffff​​ggggggggggggggggggggg
   

3. Switch to WYSIWYG and switch to source:

Entity gets doubled.

Problem can be reproduced from CKEditor 3.0 but I'm setting 4.0 as this is most likely going to be fixed in CKE 4.x.