Steps to reproduce
Load https://www.mediawiki.org/wiki/Special:AllMessages?prefix=import&lang=tr
or https://www.mediawiki.org/wiki/Special:AllMessages?prefix=Import&lang=tr
What happens?
It shows No results.
What should have happened instead?
It should show all messages starting with import like on
https://www.mediawiki.org/wiki/Special:AllMessages?prefix=import&lang=en or on
https://www.mediawiki.org/wiki/Special:AllMessages?prefix=Import&lang=en
The message keys are in English and therefor the ucfirst should be in English and not in Turkish with the mapping from i to İ.