fixup: use local variable instead of fn call

Author: sgeisler

src/hex.rs

@@ -108,7 +108,7 @@ impl<'a> DoubleEndedIterator for HexIterator<'a> {
     fn next_back(&mut self) -> Option<Result<u8, Error>> {
         let current_len = self.sl.len();
         if current_len % 2 == 1 {
-            Some(Err(Error::OddLengthString(self.sl.len())))
+            Some(Err(Error::OddLengthString(current_len)))
         } else if self.sl.is_empty() {
             None
         } else {