Support opening the archive directly

fs/contrib/archivefs.py

@@ -98,6 +98,9 @@ class ArchiveFS(FS):
     @synchronize
     def open(self, path, mode="r", **kwargs):
         path = normpath(relpath(path))
+        if path == '':
+            # We need to open the archive itself, not one of it's entries.
+            return file(self.root_path, mode)
         if 'a' in mode:
             raise Exception('Unsupported mode ' + mode)
         if 'r' in mode: