[Nmh-workers] Poor behavior of %(putaddr)

[Ken Hornstein]

Earl Hood mentioned that he was running into problems with "repl"
hanging, and I ran into the same thing as well during some testing
here, so I went and tracked down the problem.  Basically, it boils
down to the use of %(putaddr) when "num" is zero.

%(putaddr) uses the "num" register as a field width.  If "num" is zero
(and many times it is if you don't explicitly set it), then it ends up
basically performing badly (you would eventually get a whole lot of newlines
in your draft).  This has been a problem for approximately forever.

Having this just hang because of a poorly written mh-format file
seems wrong.  Suggestions on a good solution?  Fixing the format
scanner code so it behaves better is a possibility (but I'm not
sure what "better" is in this case), but I am wondering if the
format code should kick out an error when it runs into this situation.

--Ken