bug#23750: 25.0.95; bug in url-retrieve or json.el

[Leo Liu]

I have been trying to debug an issue in TernJs¹ on and off for a few
months now and it seems the cause is some nasty bug in Emacs 25. Could
someone follow the steps detailed in
https://github.com/ternjs/tern/issues/719 to reproduce the issue?

I have verified that the bug is not in Tern but Emacs i.e. under some
circumstances emacs's URL package strips some chars in the request body
which, in this case, leads to unbalanced parentheses in the JSON doc.

Leo

Footnotes: 
¹  https://github.com/ternjs/tern/issues/719