In the UPGRADE file, under "Upgrading from 1.3 or earlier", there is a note
As well as new messages, the processing of some messages has changed. If you have customized them, please compare the new format using Special:Allmessages or the relevant LanguageXX.php files:
Of the messages listed, the following are not used in any code and should be removed:
- dberrortext
- numauthors
- numedits
- numtalkauthors
- numtalkedits
- numwatchers
- searchresulttext
- showhideminor
Patch will come shortly, filing a task as a sanity check that the messages can indeed be removed