[PATCH] Return proper error valud from "parse_date()"

[PATCH] Return proper error valud from "parse_date()"

Right now we don't return any error value at all from parse_date(), and if
we can't parse it, we just silently leave the result buffer unchanged.

That's fine for the current user, which will always default to the current
date, but it's a crappy interface, and we might well be better off with an
error message rather than just the default date.

So let's change the thing to return a negative value if an error occurs,
and the length of the result otherwise (snprintf behaviour: if the buffer
is too small, it returns how big it _would_ have been).

[ I started looking at this in case we could support date-based revision
  names. Looks ugly. Would have to parse relative dates.. ]

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>