The attached pach sets localhost as the default mirror. It forces most users to edit /etc/pbuilderrc.
diff -ru pbuilder-0.141_orig/pbuilderrc pbuilder-0.141/pbuilderrc --- pbuilder-0.141_orig/pbuilderrc 2005-12-28 10:27:54.000000000 +0100 +++ pbuilder-0.141/pbuilderrc 2005-12-28 10:29:02.000000000 +0100 @@ -8,7 +8,8 @@ #EXTRAPACKAGES=gcc3.0-athlon-builder #export DEBIAN_BUILDARCH=athlon BUILDPLACE=/var/cache/pbuilder/build/ -MIRRORSITE=http://ftp.jp.debian.org/debian +MIRRORSITE=http://127.0.0.1/debian +#MIRRORSITE=http://ftp.jp.debian.org/debian #NONUSMIRRORSITE="http://ftp.jp.debian.org/debian-non-US" #OTHERMIRROR="deb http://www.home.com/updates/ ./" #export http_proxy=http://your-proxy:8080/