assert_eq failure message now multi-line related to rust pull request 42541.

Author: gilescope

tests/bench.rs

@@ -242,8 +242,9 @@ fn cargo_bench_failing_test() {
 [FINISHED] release [optimized] target(s) in [..]
 [RUNNING] target[/]release[/]deps[/]foo-[..][EXE]
 thread '[..]' panicked at 'assertion failed: \
-    `(left == right)` (left: \
-    `\"hello\"`, right: `\"nope\"`)', src[/]foo.rs:14
+    `(left == right)`
+ left: `\"hello\"`,
+right: `\"nope\"`', src[/]foo.rs:14
 [..]
 ", p.url()))
                        .with_status(101));