--- lib/python3.4/bz2.py~	2013-09-09 22:21:08.131447089 -0400
+++ lib/python3.4/bz2.py	2013-10-09 21:02:03.132950449 -0400
@@ -91,6 +91,10 @@
             mode = "ab"
             mode_code = _MODE_WRITE
             self._compressor = BZ2Compressor(compresslevel)
+        elif mode in ("x", "xb"):
+            mode = "xb"
+            mode_code = _MODE_WRITE
+            self._compressor = BZ2Compressor(compresslevel)
         else:
             raise ValueError("Invalid mode: %r" % (mode,))