[Feature Request] git blame showing only revisions from git rev-list --first-parent

Background ===

My colleagues and I disagree on how exactly to handle feature development in branches. There are approximately two camps:

Camp 1: All feature branches should be squashed after code review to a single commit before merging.

Camp 2: Leave the history of development alone, being able to trace why the feature evolved that way is useful information, never squash commits after code review.

Being somebody who leans towards the second camp I have been trying to understand the first camps objections...

Those objections seem to boil down to tracing when the feature was introduced.

I have been able to get past some of the objections by pointing out the `--first-parent` option available to `git log` and `gitk`. With that command line option they are presented with a single history of the branch and all merge commits are shown *as if squashed* (or at least that is what it looks like from my testing)

The only remaining objection is around `git blame`...

You see a problem on one line in the file, you run `git blame file.txt` and it says <rev1> was when it changed...

Now <rev1> is not on the main line of the branch but actually is a commit that was merged from one branch to another before finally being merged into the current branch in <rev2>

That is a complex nest of commits to detangle, especially when we have had some refactoring branches with multiple experiments that drag on over the course of a couple of weeks with many commits... all they want to know is <rev2>.

Yes I could (and I do try to) teach them how to find the commit where that SHA was merged into the current branch, but really they just want to be able to see the current branches SHAs only.

Doing some reading in the git blame sources I discovered that git blame takes the rev-list command line options... so I thought "hey --first-parent should work"

Except it doesn't

I suspect that this is because of how blame uses rev-list

Request ===

A command line option to `git blame HEAD -- path` that instructs that the revisions of blame be the revisions where the change was applied to the current branch not the revision where the change first originated (i.e. limit commits to `git rev-list --first-parent HEAD`)

I can get what I want with the following:

git rev-list --first-parent HEAD | awk '{print p " " $0}{p=$0}' > tmpfile && git blame -b -S tmpfile HEAD -- path && rm tmpfile

But that is a rather ugly command. Could we have something built in to git blame to make this much easier for users?

Thanks