cleanup pipe_in left overs from debugging session

tests/common/util.rs

@@ -2366,20 +2366,15 @@ impl UChild {
 
         let join_handle = std::thread::Builder::new()
             .name("pipe_in".to_string())
-            .spawn(move || {
-                let result = writer.write_all(&content);
-                let result2 = result.and_then(|()| writer.flush());
-                std::mem::drop(writer);
-
-                let result = match result2 {
+            .spawn(
+                move || match writer.write_all(&content).and_then(|()| writer.flush()) {
                     Err(error) if !ignore_stdin_write_error => Err(io::Error::new(
                         io::ErrorKind::Other,
                         format!("failed to write to stdin of child: {error}"),
                     )),
                     Ok(()) | Err(_) => Ok(()),
-                };
-                result
-            })
+                },
+            )
             .unwrap();
 
         self.join_handle = Some(join_handle);