Where is thr_getscheduler

I have a system that I have not updated since 16 Jun 06.
I read /usr/src/UPDATING and note that the 3 newest entries
do not affect me.  So, I rebuild and update my kernel and
world.  Upon rebooting, I find that firefox dies with

troutmask:kargl[202] firefox
/libexec/ld-elf.so.1: /usr/lib/libthr.so.2: Undefined symbol "thr_getscheduler"

OK, this is -current, so I rebuild and reinstall firefox.  The
firefox again gives me 
/libexec/ld-elf.so.1: /usr/lib/libthr.so.2: Undefined symbol "thr_getscheduler"

Sure enough, grepping the sources in src/lib/libthr indeed shows
that thr_getscheduler is used but never defined.

It appears that libthr has been broken since 13 Jul 06.  Is there
any time line for when libthr will be fixed?  Should an entry
be added to /usr/src/UPDATING to warn people that libthr is
broken?

-- 
Steve