uint: bugfix in trailing_zeroes()

Cargo.toml

@@ -1,7 +1,7 @@
 
 [package]
 name = "bitcoin"
-version = "0.8.0"
+version = "0.8.1"
 authors = ["Andrew Poelstra <apoelstra@wpsoftware.net>"]
 license = "CC0-1.0"
 homepage = "https://github.com/apoelstra/rust-bitcoin/"

src/util/uint.rs

@@ -202,7 +202,7 @@ macro_rules! construct_uint {
                 for i in 0..($n_words - 1) {
                     if arr[i] > 0 { return (0x40 * i) + arr[i].trailing_zeros() as usize; }
                 }
-                (0x40 * ($n_words - 1)) + arr[3].trailing_zeros() as usize
+                (0x40 * ($n_words - 1)) + arr[$n_words - 1].trailing_zeros() as usize
             }
         }