Last night I tried to do a snapshot build but unfortunately I ran into
   this...
   
   The makefile for usr.bin/vi contains...
   
      .if make(install)
      SUBDIR+=USD.doc/edit USD.doc/exref USD.doc/vi.ref USD.doc/vitut
      .endif
   
   And there is only a vi.ref -- the rest don't exist. Thus, the make
   install fails. What happened to the other directories anyway?

um.. my vi/Makefile has:

.if make(install)
SUBDIR+=docs/USD.doc/edit docs/USD.doc/exref docs/USD.doc/vi.ref docs/USD.doc/vitut
.endif

which *do* exist.

there has been some weird problems with these lately, so, it maybe
that you need to re-sup, or, cvs update -dP and try again...

.mrg.