Due to human error we've pointed all of our wiki projects nearby pages to hit English Wikipedia. This is bad for many reasons 1) Broken links on production on all our wikis other than enwiki 2) enwiki now jsonps itself. 3) enwiki will now get the sum of all traffic across all our projects for the nearby page (can it cope?!) 4) projects like French Wikipedia will get English results on Nearby.
For these reasons I suggest we lightning deploy this asap: https://gerrit.wikimedia.org/r/#/c/119416/
In terms of acceptance tests to protect this from happening again - this is not really possible due to the longstanding issues we are having with being able to test nearby with browser tests.