Appears to remove all the en-gb translation for the ParserFunction extension (The messages don't appear to have been deleted on translatewiki, or to have ever existed. I'm not sure what's the deal with that).
As a result of killing the en-gb translation, it breaks the unit tests (the #language test of the convertTests parser test) testing the language option of the convert parser function
Resolved more permanently in r94731. Thanks for spotting this.