Aug 13 2016
I think this is a major bug breaking Mediawikis since 1.26. This is a problem especially for non-English wikis containing special characters in article titles. It would be nice if this gets more attention.
Aug 6 2016
Here's a pretty dirty hotfix you probably shouldn't use:
RFC 3986 says that the HEX chars are case-insensitive. A string comparison might not be the right thing to do here.