Allow argument file to be separated for "@" prefix.

Allows shell expansion (ex: "@~/foo.cfg" cannot be expanded, "@ ~/foo.cfg"
can be).

apachedex/__init__.py

@@ -842,9 +842,12 @@ class ShlexArgumentParser(argparse.ArgumentParser):
     new_args = []
     append = new_args.append
     extend = new_args.extend
+    args = iter(args)
     for arg in args:
       if arg[:1] in self.fromfile_prefix_chars:
         filepath = arg[1:]
+        if not filepath:
+          fileath = next(args)
         new_cwd = os.path.normpath(os.path.join(
           cwd,
           os.path.dirname(filepath),