Pull requests grouping name validation

[daddykotex]

The configuration for pull requests grouping states that the name will be used as an identifier for things like the branch created to host the changes. Unfortunately, some characters, like spaces, are forbidden in branch names.

What would you do to prevent failure when someone uses a name like "Our common lib". Do you prefer:

1. validation on start up which fails because the config is valid
2. validation which warns and sanitize the name
3. sanitize the name w/o a warning
4. just document that you can't use spaces in name and hope users won't do that