Clarify exactly what needs to be backed up when upgrading Bamboo

The Bamboo Upgrade Guide says:

"Back up the three directories you identified in Step 1 — your Bamboo Home, Build Data Path and Configuration Path"

however, the default "Build Working Directory" is located inside the "Bamboo Home".

Please clarify whether the "Build Working Directory" needs to be backed up, or if Bamboo will completely regenerate it from CVS/SVN/etc. if needed.