Fixed bug

Author: michirakara

library/core/src/iter/range.rs

@@ -849,7 +849,11 @@ impl<A: Step> Iterator for ops::Range<A> {
 
     #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
-        Step::steps_between(&self.start, &self.end)
+        if self.start < self.end {
+            (0, Some(0));
+        } else {
+            Step::steps_between(&self.start, &self.end)
+        }
     }
 
     #[inline]