Fixed bug where merge request JSON would show

What does this MR do?

Fixes a bug that would cause the merge request to load JSON instead of the HTML page. This was caused by an AJAX being made to /namespace/merge_request/1 instead of /namespace/merge_request/1.json.

What are the relevant issue numbers?

Closes #28909 (closed)

@brycepj can you check please seeing as you are the only one able to reproduce it?

approved this merge request

@iamphill looks fixed to me! I can't believe this is all it took Thanks for doing this

@brycepj If we ever see something like it is usually because we can load JSON & HTML from the same URL so Chrome (& maybe other browsers) presume it is the same page & just loads the last cached result which is usually the JSON. Simply adding .json to end tells the browser its a different page

assigned to @filipa

Thank you @iamphill

mentioned in commit 07eac529

merged

Picked into 9-1-stable, will go into 9.1.4

mentioned in commit 05919a01