Fix parenthesization of chained comparisons containing bailout

Author: dtolnay

src/fixup.rs

@@ -547,6 +547,9 @@ fn scan_right(
                 return Scan::Consume;
             }
             let binop_prec = Precedence::of_binop(&e.op);
+            if binop_prec == Precedence::Compare && fixup.next_operator == Precedence::Compare {
+                return Scan::Consume;
+            }
             let right_fixup = fixup.rightmost_subexpression_fixup(false, false, binop_prec);
             let scan = scan_right(
                 &e.right,