2.2.0 config files

A colleague was upgrading some boxes from (I think) 2.1.10 to 2.2.0, and says that expansions of the form %{Foo:-0} stopped working, and had to be replaced with %{%{Foo}:-0} Is that expected? I don't see anything in the ChangeLog, apart from 2.2.0 claims to be "100% configuration file compatible with 2.1.x" Thanks, Brian