tsvector that can't be dumped/reloaded in 8.3beta

I was unable to dump from beta1 to beta2, and I narrowed it down to this
simpler case:

test=> select tsvectorin(tsvectorout(
to_tsvector($foo$ a.b.cd/x=mnop.q\ $foo$)
));
ERROR: syntax error in tsvector: "'a.b.cd':2 'a.b.cd/x':1 '/x=mnop.q
\':3"

This has the same result on beta1 and beta2.

I'm using en_US.UTF-8 on FreeBSD.

Regards,
Jeff Davis