New and interesting replication issues with 9.2.8 sync rep

Just got a report of a replication issue with 9.2.8 from a community member:

Here's the sequence:

1) A --> B (sync rep)

2) Shut down B

3) Shut down A

4) Start up B as a master

5) Start up A as sync replica of B

6) A successfully joins B as a sync replica, even though its transaction
log is 1016 bytes *ahead* of B.

7) Transactions written to B all hang

8) Xlog on A is now corrupt, although the database itself is OK

Now, the above sequence happened because of the user misunderstanding
what sync rep really means.  However, A should not have been able to
connect with B in replication mode, especially in sync rep mode; that
should have failed.  Any thoughts on why it didn't?

I'm trying to produce a test case ...

-- 
Josh Berkus
PostgreSQL Experts Inc.
http://pgexperts.com