feature request: .blameignore

Hello git community,

I'm completely new here, and maybe my request is dumb, has already a better solution, or I did not fully understand git. Please tell my if so. I stumbled upon this idea while following the django developers mailing list, people there discussing whether nor not to adopt *black* (https://github.com/ambv/black, a python code formatting tool) as enhancement in the development cycle. One of the main arguments against black was that it changes git history by masking git blame. Whenever a git commit with only a black formatting change is committed, you can't easily see using git blame WHO did actially write a line of code *before* that commit. It is possible to look further manually, and they said there are tools like git-hyper-blame that circumvent that problem, but I always asked myself since I use git, why isn't there a simple possibility how I can e.g. fix a whitespace code "error", or do a code reformatting WITHOUT taking away the original author's credits for that line.

I know, there are some counter arguments about that:  e.g. whitespace changes could lead to programming errors too, even to compiler errors, depending on the language, and how the compiler engine treats whitespace.

I don't suggest git to ignore whitespace (or whatever) changes in the blame history automatically.

What I suggest is: let git accept a file like .blameignore, .gitblameignore, .gitblame etc., you name it. In my simply suggest, I would see that file as one-hash-per-line that is ignored by git blame. And for the sake of convenience, add a git option to add that hash automatically:

    git commit -m "fix whitespace" --blame-ignore

This would add this commit's hash to the .gitblameignore (or whatever) file:

4070ddcdd3d3cc45ec7952e1b37ab374aed9083c # fix whitespace

and a "git blame any_file.txt" would ignore this one commit and show the last commit's author of changed lines.

Even better would it be to allow chunks to be excluded, because bad commit habits of whitespace AND real code changes at the same time are not possible to undo later - except there would be a .gitblameignore file.

It would even be possible to incorporate this into tht .gitignore file, with a section, or a certain prefix...

IMHO, this would allow better per-project maintainance of blame history which could be changed later in time and  re-fixed if done wrong - all within git history itself.

I'd love to hear what you think about that.

Yours,

Christian