RMAIL and movemail?

[John <jpff@codemist.co.uk>]

I am running the latest emacs from master but I am not sure when this
started to happen.

My raw mail box lives on a mail server machine on the LAN and i read
email either directly there (with alpine usually) or from time to time
I read mail into RMAIL on emacs on this computer.  For some time I
have not read it into emacs but now it does not work, nor for the
other main emacs user.  It may have been  triggered by a replacement
of the mail server (due to a failing disk possible) as the other user
noticed this yesterday.

Running emacs and looking at RMAIL file I type g, and it fails

Debugger entered--Lisp error: (wrong-type-argument stringp nil)
  string-match("^\\(imap\\|pop\\)s?$" nil nil)
  rmail-remote-proto-p(nil)
  rmail-insert-inbox-text(("/snout/home/aff/mbox") t)
  rmail-get-new-mail-1(nil ("/snout/home/aff/mbox") nil)
  rmail-get-new-mail()
  rmail()
  myrmail()
  funcall-interactively(myrmail)
  call-interactively(myrmail nil nil)
  command-execute(myrmail)
  command-line-1(("-f" "myrmail"))
  command-line()
  normal-top-level()

Absolutely repeatable.  The variable proto is nil and the mail box is
set by 
(setq rmail-primary-inbox-list '("/snout/home/aff/mbox"))
where /snout if nfs mounted from the server to the local machine
This was working until yesterday.  What have I done wrong?  I have
tried tracing the rail-get-new-mail and it looks OK as far as it goes.

Another data point, ^U g works but clearly does not delete the primary
mail.   I have checks the computer has read/write access to the nfs
mounted disk.  

==John ffitch