fix(criterion_compat): properly wait for python benchmark process

Author: GuillaumeLagrange

crates/criterion_compat/benches/criterion_integration/external_process.rs

@@ -23,17 +23,19 @@ fn python_fibonacci(c: &mut Criterion) {
         .is_ok();
 
     if has_python3 {
-        let process = create_command()
+        let mut process = create_command()
             .stdin(Stdio::piped())
             .stdout(Stdio::piped())
             .spawn()
             .expect("Unable to start python process");
 
         let mut stdin = process
             .stdin
+            .take()
             .expect("Unable to get stdin for child process");
         let stdout = process
             .stdout
+            .take()
             .expect("Unable to get stdout for child process");
         let mut stdout = BufReader::new(stdout);
         c.bench_function("fibonacci-python", |b| {
@@ -51,6 +53,9 @@ fn python_fibonacci(c: &mut Criterion) {
         });
 
         // Ensure that your child process terminates itself gracefully!
+        process
+            .wait()
+            .expect("Child process did not terminate gracefully");
     }
 }