Afaik he took Code Typhon as basis, and they use trunk too. IIRC because of newer ARM support.
Anyway, the instability of 2.7.1 shouldn't be exaggerated, but status changes daily, and there will be small breakages. (and if you say e.g. "I have 2.7.1 of late june", nobody can give you a list of problems in that version)