pksrc variable MAIL_CMD not defined for NetBSD 3.1???

I have a fresh install of NetBSD 3.1:

        -> uname -v
        NetBSD 3.1 (GENERIC) #0: Tue Oct 31 04:42:59 UTC 2006
builds@xxxxxxxxxxxxx:/home/builds/ab/netbsd-3-1-RELEASE/mac68k/200610302053Z-obj/home/builds/ab/netbsd-3-1-RELEASE/src/sys/arch/mac68k/compile/GENERIC

and pkgsrc from HEAD (updated 2006-12-21).

In mk.conf, I have PKGSRC_MESSAGE_RECIPIENTS=mep, but when installing
mail/imap-uw, I get

-sPackage imap-uw-2004gnb2 installed on dummy: not found
*** Error code 127

and the install exits.

MAIL_CMD resolves to an empty string:

        -> make -V MAIL_CMD

        ->


On a Mac OS X system (also w/ pkgsrc updated 2006-12-21, and where things work
as expected), MAIL_CMD eventually resolves to /usr/bin/mail:

        -> bmake -V MAIL_CMD
        ${TOOLS_CMDLINE_${_TOOLS_VARNAME.mail}}
        -> bmake -V _TOOLS_VARNAME.mail
        MAIL_CMD
        -> bmake -V TOOLS_CMDLINE_MAIL_CMD
        ${TOOLS_CMDLINE.mail}
        -> bmake -V TOOLS_CMDLINE.mail
        ${TOOLS_PATH.mail}
        -> bmake -V TOOLS_PATH.mail
        ${TOOLS_PLATFORM.mail:C/^/_asdf_/1:M_asdf_*:S/^_asdf_//}
        -> bmake -V TOOLS_PLATFORM.mail
        /usr/bin/mail


However, working backwards on the 3.1 system, I see

        -> make -V TOOLS_PLATFORM.mail
        /usr/bin/mail
        -> make -V TOOLS_PATH.mail

        -> make -V TOOLS_CMDLINE.mail

        -> make -V TOOLS_CMDLINE_MAIL_CMD

        -> make -V _TOOLS_VARNAME.mail
        MAIL_CMD


A workaround is to set MAIL_CMD for the install, but I might be missing
something else that should be obvious or something is broken here.

Any suggestions on a proper fix?

Thanks,
Mark