When putting a VC together with four or five EX4300 switches, I have found that there are times when the configuration has all interfaces it can currently support, not just the interfaces that exist. This can be troublesome, especially for RSTP.
I’ve gotten into the habit of deleting all interfaces first, and only creating the interfaces needed:
email@example.com# delete interfaces
firstname.lastname@example.org# delete protocols rstp
email@example.com# wildcard range set interfaces xe-[0-1]/0/[0-47]
firstname.lastname@example.org# wildcard range set interfaces et-0/0/[48-49]
email@example.com# set protocols rstp interface all
I don’t know if anyone else has reproduced this, I’m waiting on DACs for my lab in order to reproduce and submit a patch.