Today I had one notebook that I checked in to source control. Then of course it is read-only on the file system. When opening the notebook using local ipython/jupyter notebook server and trying to save it, then the following error comes up:

Permission denied: blablabla.ipynb

also the temporary file .~blablabla.ipynb is generated with read-only flag, which looks like exact copy of original notebook.

The problem is that this file is not cleaned up after this error!

This causes the notebook to fail saving even when read-only flag is removed.

Manually removing this temporary file is the current workaround.

windows 7, 64 bit

The version of the notebook server is 4.0.6 and is running on:
Python 2.7.9 (default, Dec 10 2014, 12:24:55) [MSC v.1500 32 bit (Intel)]