add test that was failing from tedh

Author: nikomatsakis

src/test/run-pass/alt-with-ret-arm.rs

@@ -0,0 +1,11 @@
+fn main() {
+    // sometimes we have had trouble finding
+    // the right type for f, as we unified
+    // bot and u32 here
+    let f = alt uint::from_str("1234") {
+        none { ret () }
+        some(num) { num as u32 }
+    };
+    assert f == 1234u32;
+    log(error, f)
+}