[Quilt-dev] fold seems to lose the patch preamble

[Martin Bligh]

If I fold in a new patch, it seems to lose the header info rather
than append it, which is a shame.

I made a foul hack to fix it, but I'm sure it's not the right way
to do it. It's made harder by the fact that fold reads from stdin
(which also seems inconsistent with all the other commands), but
I'm sure someone less incompetent with bash scripting could fix
it much more nicely ;-)

M.