Comment 1 for bug 10196

Blocker seems excessive dude, but fully agreed it's very irritating. Problem is
that firefox doesn't have any profile migration code that works, so the only way
has been to blow away customisations on every upgrade (otherwise you're in
random segfaults, gecko/xul not rendering properly etc territory).
This should not now be necessary assuming they keep something approaching
compatability now they're stable.