and committed already. This is mostly a helpful addition to "Oh, I didn't
lint those!"
Also, added the basic '--pr', which gives you the list of files
changed in the very last commit, so you don't have to specify which
revision you mean.
Now it doesn't print things the user doesn't care about, like empty
lint passes, or broken linters that aren't relevant to the current
project.
Added a test pass to ensure it doesn't blow up when running against
an empty stage.
Elf M. Sternberg