Git blame behavior when file is not added to git

[MarkRx]

Version

7.3.0.202506031305-r, 5.6.0.201912101111-r

Operating System

Windows

Bug description

If a file is within the git workspace but not added to git then git blame with the CLI will throw an error:

$ git status
On branch master
Untracked files:
(use "git add ..." to include in what will be committed)
foo.txt

nothing added to commit but untracked files present (use "git add" to track)

$ git blame foo.txt
fatal: no such path 'foo.txt' in HEAD

JGit returns null in this case. Perhaps this should be an exception?

import java.io.File

import org.eclipse.jgit.lib.RepositoryBuilder
import org.eclipse.jgit.api.Git

def repo = new RepositoryBuilder().setWorkTree(new File("$projectDir")).setMustExist(true).build()

def git = new Git(repo)
def blameCommand = git.blame()
blameCommand.setFilePath("foo.txt")
def res = blameCommand.call()

println(res)

Actual behavior

In jgit 5.5.1.201910021850-r a BlameResult was returned with a the file showing up as new
In jgit 5.6.0.201912101111-r and above the behavior changed and null is returned

Expected behavior

Either

1. An exception is thrown (since git CLI treats this as an error)
2. The meaning of a null result is explicitly documented

Relevant log output

Other information

No response