>> By the time "make build" got that far, it had overwritten your
>> /usr/share/mk with new bsd.*.mk files. Those may work properly with
>> your 1.3.2 make, or they may try and use new features which aren't in
>> the old 1.3.2 make binary.

>Oops!  I'd better make sure I have backups of the source tree so I don't 
>have to sup it all again in case I have to re-install from the binaries.

"make build" doesn't clobber your source tree; it's the "live" tree
you have to worry about.  But if you set DESTDIR, you don't have to
worry about that until you do a "make install" (with no DESTDIR).