put 0 in shape first, rather than result of first edge

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/src/lib.rs b/src/lib.rs
index f01a3fa72b4c77808bb483cc96bfd3595c3d2852..58bbc56ea29fc80dc5839ff40fff8921016cac90 100644 (file)
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -24,8 +24,9 @@ pub fn read_vertices() -> impl Iterator<Item=Shape> {
       let cl = cx.to_ascii_lowercase();
       let d = if cx == cl { -1 } else { 1 };
       let i = cl as usize - 'x' as usize;
+      let was = current;
       current[i] += d;
-      current
+      was
     }).collect_vec();
     assert_eq!(current, Point::default());
     shape_abut_zero(&mut points);