From 121d81bdf78473158dcbe5be8446f1bbe2859374 Mon Sep 17 00:00:00 2001
From: Marc Wouts <marc.wouts@gmail.com>
Date: Mon, 12 Nov 2018 21:27:03 +0100
Subject: [PATCH] freeze_metadata option only updates jupytext metadata #124

---
 jupytext/jupytext.py | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/jupytext/jupytext.py b/jupytext/jupytext.py
index 8ff523779..34a8fe2d6 100644
--- a/jupytext/jupytext.py
+++ b/jupytext/jupytext.py
@@ -59,10 +59,9 @@ def reads(self, s, **_):
             lines = lines[pos:]
 
         if self.freeze_metadata:
-            metadata['jupytext'] = {'metadata_filter': {
-                'notebook': {'additional': list(metadata.keys()), 'excluded': 'all'}}}
-            metadata['jupytext']['metadata_filter']['cells'] = {
-                'additional': list(cell_metadata), 'excluded': 'all'}
+            metadata.setdefault('jupytext', {})['metadata_filter'] = {
+                'notebook': {'additional': list(metadata.keys()), 'excluded': 'all'},
+                'cells': {'additional': list(cell_metadata), 'excluded': 'all'}}
 
         set_main_and_cell_language(metadata, cells, self.format.extension)