Steps to replicate the issue (include links if applicable):

• Visit https://zh.wikipedia.org/zh-my/Wikipedia:%E9%A6%96%E9%A1%B5
• Run mw.util.getUrl('Foo') in developer console

What happens?:
The variant zh-my is not present in the response

mw.util.getUrl('Foo')
'/wiki/Foo'

What should have happened instead?:

mw.util.getUrl('Foo')
'/zh-my/Foo'

Software version (on Special:Version page; skip for WMF-hosted wikis like Wikipedia):

Other information (browser name/version, screenshots, etc.):