Automatic formatting inserts a space between the comment marker `#` and text in the Python extension, so without the allowance for whitespace then `"editor.formatOnType": true` breaks all region markers.
ClosesMicrosoft/vscode-python#1073 and Microsoft/vscode-python#33
Python uses a ["string prefix"](https://docs.python.org/3/reference/lexical_analysis.html#string-and-bytes-literals) to denote bytes literals (`b''`), raw strings (`r''`), and formatted string literals (`f''`). This change makes it so that when one types `r'` in VS Code, the string will be auto-closed as `r''` (as an example).
Python also supports multiple string prefixes for a single literal. I've tested that typing `fr'` will auto-close to `fr''`, and so forth.