With bug #9418 resolved, I've tested again with a Windows 2008R2 RODC join. Attached are logs and traces.
Created attachment 8322 [details] Keytab for pcap of failure
Created attachment 8323 [details] PCAP format capture of the failed dcpromo
Created attachment 8324 [details] wintest output
Fixed with the patches from https://bugzilla.samba.org/show_bug.cgi?id=9481