fix: keep existing contents in create_file

src/lib.rs

@@ -19,6 +19,12 @@ fn safe_create_file(path: PathBuf) -> Result<File, std::io::Error> {
     OpenOptions::new().write(true).create_new(true).open(path)
 }
 
+// truncate(false) keeps an existing file's contents, which is what callers creating
+// an empty __init__.py want
 fn create_file(path: PathBuf) -> Result<File, std::io::Error> {
-    OpenOptions::new().write(true).create(true).open(path)
+    OpenOptions::new()
+        .write(true)
+        .create(true)
+        .truncate(false)
+        .open(path)
 }