[fix shortenPath when working on invalid directories
John Meacham <john@repetae.net>**20080215040425] hunk ./Ho/Build.hs 99
-    --print (x,cd,h)
-    let f d = d >>= \d -> getPrefix d x >>= \ ('/':rest) -> return rest
+    let f d = do
+            d <- d
+            '/':rest <- getPrefix d x
+            return rest