BZ2File now uses the compresslevel argument given by the caller,
instead of ignoring it and always using a compression level of 9.
diff --git a/Lib/bz2.py b/Lib/bz2.py
index cc71ae0..cbf5233 100644
--- a/Lib/bz2.py
+++ b/Lib/bz2.py
@@ -75,11 +75,11 @@
         elif mode in ("w", "wb"):
             mode = "wb"
             mode_code = _MODE_WRITE
-            self._compressor = BZ2Compressor()
+            self._compressor = BZ2Compressor(compresslevel)
         elif mode in ("a", "ab"):
             mode = "ab"
             mode_code = _MODE_WRITE
-            self._compressor = BZ2Compressor()
+            self._compressor = BZ2Compressor(compresslevel)
         else:
             raise ValueError("Invalid mode: {!r}".format(mode))