Auto completion for file paths with spaces

Jupyter with python does auto-completion of the file paths when tab is pressed, but the auto-completion feature does not work if the file path has spaces in it.

No source file, entry point, or test is named. First reproduce file-path completion in Jupyter Notebook with a path containing spaces, then trace the completion behavior and identify the relevant tests; done means pressing Tab completes such paths reliably.

Written by the indexing model from the issue text.