Ensure that we get the text as text (not json)

Fixes #1124 and jupyterlab/jupyter-collaboration#214

CHANGELOG.md

@@ -5,6 +5,7 @@ Jupytext ChangeLog
 ----------
 
 **Fixed**
+- We have fixed a notebook corruption issue when using Jupytext with Jupyter-Collaboration ([#1124](https://github.com/mwouts/jupytext/issues/1124), [jupyter-collaboration #214](https://github.com/jupyterlab/jupyter-collaboration/issues/214)).
 - The `rst2md` tests have been fixed by requiring `sphinx<8` ([#1266](https://github.com/mwouts/jupytext/issues/1266))
 - Some dependencies of the JupyterLab extensions were updated ([#1272](https://github.com/mwouts/jupytext/issues/1272), [#1273](https://github.com/mwouts/jupytext/issues/1273), [#1280](https://github.com/mwouts/jupytext/issues/1280), [#1285](https://github.com/mwouts/jupytext/issues/1285), [#1290](https://github.com/mwouts/jupytext/issues/1290))
 - The pre-commit hook is now compatible with log.showsignature=True ([#1281](https://github.com/mwouts/jupytext/issues/1281)). Thanks to [Justin Lecher](https://github.com/jlec) for this fix.

src/jupytext/contentsmanager.py

@@ -299,7 +299,11 @@ def read_one_file(alt_path, alt_fmt):
 
                 self.log.info(f"Reading SOURCE from {alt_path}")
                 text = self.super.get(
-                    alt_path, content=True, type="file", format=format
+                    alt_path,
+                    content=True,
+                    type="file",
+                    # Don't use the parent format, see https://github.com/mwouts/jupytext/issues/1124
+                    format=None,
                 )["content"]
                 return reads(text, fmt=alt_fmt, config=config)
 

src/jupytext/version.py

@@ -1,3 +1,3 @@
 """Jupytext's version number"""
 
-__version__ = "1.16.4"
+__version__ = "1.16.5-dev"