How to run massive portmaster update without repeated interruptions?

[Thomas Mueller]

When updating many ports with portmaster, I get frequent interruptions with a prompt such as
===>>> Delete gstreamer-0.10.35.tar.bz2? y/n [n]

How do I avoid this inefficiency?  I don't see any way to say "yes, and please don't ask again!"

My /usr/local/etc/portmaster.rc is

MAKE_PACKAGE=gopt
SAVE_SHARED=wopt
PM_LOG=/var/log/portm.log
NO_BACKUP=Bopt

I don't remember this ever happening when I used portupgrade.

Tom