Freezes are noted in pkgsrc/doc/CHANGES-YYYY, in this case with
CHANGES-2007 coantaining

        mk/bsd.pkg.mk: started freeze for pkgsrc-2007Q4 branch [agc 2007-12-18]

I don't think there's any need to back this out.  Either it will build
or it won't during bulk builds, and either is ok, really.