Fix whitespace bug in dul-web.

Had a tab that was syntactically correct, but since python treats tabs
as 8 spaces rather than 4 it resulted in incorrect behavior.

bin/dul-web

@@ -30,7 +30,7 @@ if __name__ == "__main__":
     else:
         gitdir = os.getcwd()
 
-	backend = DictBackend({"/": Repo(gitdir)})
+    backend = DictBackend({"/": Repo(gitdir)})
     app = HTTPGitApplication(backend)
     # TODO: allow serving on other ports via command-line flag
     server = make_server('', 8000, app)