Installworld broken on RELENG_6 by libc commit?

[David Booth]

On Wednesday 24 October 2007, Alson van der Meulen wrote:
> Hello,
>
> My installworld of RELENG_6 from a few hours ago failed with this
> error (from memory):
> /lib/libncurses.so.6: undefined symbol: __mb_sb_limit
>
> This broke everything that depended on libncurses, plus PAM. I had
> to force a reboot via DDB and copy /usr/obj/lib/libc/libc.so.6 to
> /lib using binaries from /rescue to fix it so I could run make
> installworld again.
>
> I upgraded from RELENG_6 of October, 22. I believe I followed the
> procedure from /usr/src/UPDATING fairly closely, except for the
> reboot to single user part after installing the kernel:
> mergemaster -p && make buildworld && make kernel && make
> installworld && mergemaster && make delete-old
>
> I would expect libc to be installed before other libs. The
> securelevel was -1, so it should be no problem to overwrite libc.
>
> Did I do something wrong or is this a bug/missing entry in
> UPDATING?
>
> regards,
> Alson
>
It is not something you did.  I had the same problem and have just 
recovered from it.