[wp-testers] Menus Custom Link - target= - wp3b1 -> wp3b2

[Andrew Nacin]

We still support target=_blank. Actually, the schema supports for
target=anything. So any menu item that had target=_self at one point stored
will continue to display that.

Since it's constantly evolving, we've only cleaned out problematic menu
metadata on upgrade, while we were making major schema changes earlier in
the cycle. In general, I've been telling those who report menu bugs to clear
out all menu data and try again to reproduce it first.