Setup.hs: fix off-by-one error the change count in the version info

The difference between "One change" and "No changes" is very noticeable.

Setup.hs

@@ -398,12 +398,12 @@ extractDarcsVersion distFlag =
      let from = case tags of
                   [] -> []
                   tag:_ -> ["--from-tag="++tag]
-         dates <- patches `fmap` readProcess "darcs" ("changes":from) ""
+     dates <- (init' . patches) `fmap` readProcess "darcs" ("changes":from) ""
 --   let dates = init' (filter ((`notElem` [""," "]).take 1) changes)
      whatsnew <- tryIOE $ lines `fmap` readProcess "darcs" ["whatsnew","-s"] ""
      return (listToMaybe tags,listToMaybe dates,
              length dates,either (const 0) length whatsnew)
-
+  where
     init' [] = []
     init' xs = init xs