Proper shell overhead computation

src/benchmark/scheduler.rs

@@ -33,7 +33,7 @@ impl<'a> Scheduler<'a> {
 
     pub fn run_benchmarks(&mut self) -> Result<()> {
         let mut executor: Box<dyn Executor> = match self.options.executor_kind {
-            ExecutorKind::Mock(ref shell) => Box::new(MockExecutor::new(shell)),
+            ExecutorKind::Mock(ref shell) => Box::new(MockExecutor::new(shell.clone())),
             ExecutorKind::Shell(ref shell) => Box::new(ShellExecutor::new(shell, &self.options)),
         };