To be editable in the system, a book needs to be built with buglinks turned on, which requires a BZPRODUCT and BZCOMPONENT to be set in the content spec. We can't do this client-side unintrusively. (it could be done by saving the current version of the spec, writing a new version with these things turned on, pushing that, building, then restoring the old state; but that's intrusive) So we rely on the author having the spec setup on the server in a particular way. When a book is built for some other purpose, it may have these things turned off, which will make docs hack system builds uneditable. In that case, the system should float a notice on the book saying what's up, and how to fix it.
Fixed now that we can force bug links on.