Unable to save in an 'untitled folder' directory

[wood-chris]

Describe the bug

Saving a notebook in an "untitled folder" generates an error

To Reproduce
Steps to reproduce the behavior:

1. Run a jupyter notebook session

2. Click on New -> New Folder

3. This creates a directory called "Untitled Folder"

4. Enter this folder, and create a new notebook }

5. File -> Save as shows Untitled%20Folder - adding a file name after this, ending up with Untitled%20Folder/my_notebook.ipynb and click save. Error shows:

    ```Unexpected error while saving file: Untitled%%20Folder/test.ipynb [Errno 2] No such file or directory: '/Users/chris/Untitled%%20Folder/test.ipynb'```
   

   it looks like it's added an extra percent symbol in the directory name

Expected behavior
The notebook should save without error!

Screenshots
If applicable, add screenshots to help explain your problem.

Desktop (please complete the following information):

• OS: macOS Catalina
• Browser: Chrome
• Version: Version 89.0.4389.90 (Official Build) (x86_64)

[kevin-bates]

Hi @wood-chris - thank you for opening this issue. I can reproduce this (even back to Notebook 5.7.8) and would characterize the issue as "SaveAs into space-separated folder fails". We'll need to take a look.

In the meantime, you should be able to work around this via Duplicate/Rename/{modify}/Save/Delete{original} or use the Lab extension as I'm unable to reproduce it using jupyter lab.