Preserve values "None" in the notebook metadata (#802)

mwouts · Jun 10, 2021 · d28c175 · d28c175
1 parent 1cfcbd2
commit d28c175
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Showing 2 changed files with 6 additions and 2 deletions.
diff --git a/jupytext/header.py b/jupytext/header.py
@@ -143,7 +143,7 @@ def recursive_update(target, update):
     for key in update:
         value = update[key]
         if value is None:
-            target.pop(key, None)
+            del target[key]
         elif isinstance(value, dict):
             target[key] = recursive_update(target.get(key, {}), value)
         else:
@@ -225,7 +225,9 @@ def header_to_metadata_and_cell(
 
     if ended:
         if jupyter:
-            recursive_update(metadata, yaml.safe_load("\n".join(jupyter))["jupyter"])
+            extra_metadata = metadata
+            metadata = yaml.safe_load("\n".join(jupyter))["jupyter"]
+            recursive_update(metadata, extra_metadata)
 
         lines_to_next_cell = 1
         if len(lines) > i + 1:

diff --git a/tests/test_cli.py b/tests/test_cli.py
@@ -1376,3 +1376,5 @@ def test_round_trip_with_null_metadata_792(tmpdir, cwd_tmpdir, python_notebook):
     write(nb, "test.ipynb")
     jupytext(["--to", "py:percent", "test.ipynb"])
     jupytext(["--to", "ipynb", "test.py"])
+    nb = read("test.ipynb")
+    assert nb.metadata.kernelspec.env is None