A relative path in core.excludesFiles is not resolved against repository root

[tomaswolf]

C git apparently resolves a relative path in core.excludesFile against the repository worktree root, whereas JGit resolves it against the current directory. Witness:

~/tmp $ mkdir exclusiontest
~/tmp $ cd exclusiontest
~/tmp/exclusiontest $ git init
Initialized empty Git repository in C:/Users/THWO/tmp/exclusiontest/.git/

~/tmp/exclusiontest (master) $ mkdir sub
~/tmp/exclusiontest (master) $ echo "ignoring" > sub/myexclusions
~/tmp/exclusiontest (master) $ echo -e '\texcludesFile = sub/myexclusions' >> .git/config
~/tmp/exclusiontest (master) $ cat .git/config
[core]
        repositoryformatversion = 0
        filemode = false
        bare = false
        logallrefupdates = true
        symlinks = false
        ignorecase = true
        excludesFile = sub/myexclusions

~/tmp/exclusiontest (master) $ git status
On branch master

No commits yet

Untracked files:
  (use "git add <file>..." to include in what will be committed)
        sub/

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

~/tmp/exclusiontest (master) $ echo "foo" > foo
~/tmp/exclusiontest (master) $ echo "foo" > ignoring
~/tmp/exclusiontest (master) $ echo "foo" > sub/foo
~/tmp/exclusiontest (master) $ echo "foo" > sub/ignoring
~/tmp/exclusiontest (master) $ git status
On branch master

No commits yet

Untracked files:
  (use "git add <file>..." to include in what will be committed)
        foo
        sub/

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

~/tmp/exclusiontest (master) $ cd sub
~/tmp/exclusiontest/sub (master) $ git status
On branch master

No commits yet

Untracked files:
  (use "git add <file>..." to include in what will be committed)
        ../foo
        ./

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

~/tmp/exclusiontest/sub (master) $ git ls-files --exclude-standard -oi | git check-ignore -vn --stdin
sub/myexclusions:1:ignoring     ignoring

~/tmp/exclusiontest/sub (master) $ cd ..
~/tmp/exclusiontest (master) $ git ls-files --exclude-standard -oi | git check-ignore -vn --stdin
sub/myexclusions:1:ignoring     ignoring
sub/myexclusions:1:ignoring     sub/ignoring

~/tmp/exclusiontest (master) $ jgit-7.7.1 status
Picked up _JAVA_OPTIONS: -Duser.language=en
On branch master
Untracked files:

        foo
        sub/foo
        sub/myexclusions

~/tmp/exclusiontest (master) $ cd sub
~/tmp/exclusiontest/sub (master) $ jgit-7.7.1 status
Picked up _JAVA_OPTIONS: -Duser.language=en
On branch master
Untracked files:

        foo
        ignoring
        sub/foo
        sub/ignoring
        sub/myexclusions

~/tmp/exclusiontest/sub (master) $

Expected: JGit resolves a relative path the same way C git does; i.e., against the repository worktree root.

Note: I set core.excludesFile here in .git/config, but the behavior is the same if you use ~/.gitconfig instead.