Is your feature request related to a problem? Please describe.

When making changes to Black's source, including when switching between branches, it's necessary to manually clear the cache directory to view the changes in formatting.

Describe the solution you'd like

A --no-cache option to bypass reading from the cache. This would make development much faster for me.

Describe alternatives you've considered

Continue manually clearing the cache, or adding tons of extra newlines at the end of the file to force cache not to match

Additional context

Should this flag also bypass writing to the cache? Or should that be a separate flag, or not at all?