worktree: remove "the_repository" from is_current_worktree()

is_current_worktree() compares the gitdir of the worktree to the gitdir
of "the_repository" and returns true when they match. To get the gitdir
of the worktree it calls get_workree_git_dir() which also depends on
"the_repository". This has the effect that even if "wt->path" matches
"wt->repo->worktree" is_current_worktree(wt) will return false when
"wt->repo" is not "the_repository" which is confusing.

The use of "the_repository" in is_current_wortree() comes from
replacing get_git_dir() with repo_get_git_dir() in 246deea
(environment: make `get_git_dir()` accept a repository, 2024-09-12). In
get_worktree_git_dir() it comes from replacing git_common_path() with
repo_common_path() in 07242c2 (path: drop `git_common_path()`
in favor of `repo_common_path()`, 2025-02-07). In both cases we have
a repository instance available so use that instead. This means
that a worktree "wt" is always considered current when "wt->path"
matches "wt->repo->worktree" and so the worktree returned by
get_worktree_from_repository() is always considered current.

Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: phillipwood

worktree.c

@@ -58,7 +58,7 @@ static void add_head_info(struct worktree *wt)
 
 static int is_current_worktree(struct worktree *wt)
 {
-	char *git_dir = absolute_pathdup(repo_get_git_dir(the_repository));
+	char *git_dir = absolute_pathdup(repo_get_git_dir(wt->repo));
 	char *wt_git_dir = get_worktree_git_dir(wt);
 	int is_current = !fspathcmp(git_dir, absolute_path(wt_git_dir));
 	free(wt_git_dir);
@@ -78,7 +78,7 @@ struct worktree *get_worktree_from_repository(struct repository *repo)
 	wt->is_bare = !repo->worktree;
 	if (fspathcmp(gitdir, commondir))
 		wt->id = xstrdup(find_last_dir_sep(gitdir) + 1);
-	wt->is_current = is_current_worktree(wt);
+	wt->is_current = true;
 	add_head_info(wt);
 
 	free(gitdir);
@@ -229,9 +229,9 @@ char *get_worktree_git_dir(const struct worktree *wt)
 	if (!wt)
 		return xstrdup(repo_get_git_dir(the_repository));
 	else if (!wt->id)
-		return xstrdup(repo_get_common_dir(the_repository));
+		return xstrdup(repo_get_common_dir(wt->repo));
 	else
-		return repo_common_path(the_repository, "worktrees/%s", wt->id);
+		return repo_common_path(wt->repo, "worktrees/%s", wt->id);
 }
 
 static struct worktree *find_worktree_by_suffix(struct worktree **list,