Write two newlines intentionally

compiler/rustc_interface/src/passes.rs

@@ -564,8 +564,7 @@ fn hash_iter_files<P: AsRef<Path>>(
                             write!(file, " checksum:{checksum_hash} file_len:{file_len}")
                         })?;
                 }
-                writeln!(file)?;
-                writeln!(file)?;
+                write!(file, "\n\n")?;
             }
 
             // Emit a fake target for each input file to the compilation. This