--dry doesn't produce any output

[amueller]

it seems to me that --dry doesn't produce any output because it's using the logger using info level.
What I would like to achieve is to ensure that all files have a license header in my continuous integration. I thought I could check if dry gave any output, but it never does.

[amueller]

if I change verbosity to -v -v -v it tells me that many files would be changed, even though they remain the same.

[Igor1306]

Hello, really useful issue.