Overriding the tools config is painful
Created originally on Bitbucket by lothiraldan (Boris FELD)
In format-source, we only define the per-tool configuration if the top-level
formatsource.TOOL is not defined by the user.
The side-effect is that it's not possible to redefine a sub-configuration value for tool (for example
formatsource.black:version_regex) without setting also the top-level configuration (for example
formatsource.black). And as we need to define the top-level configuration, we also need to define every other sub-configuration values (for example
This makes it very difficult for users to override a sub-configuration value for the tool we support by default.