worktree.c: zero new 'struct worktree' on allocation

This keeps things a bit simpler when we add more fields, knowing that
default values are always zero.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: pclouds

worktree.c

@@ -91,16 +91,11 @@ static struct worktree *get_main_worktree(void)
 	if (parse_ref(path.buf, &head_ref, &is_detached) < 0)
 		goto done;
 
-	worktree = xmalloc(sizeof(struct worktree));
+	worktree = xcalloc(1, sizeof(*worktree));
 	worktree->path = strbuf_detach(&worktree_path, NULL);
-	worktree->id = NULL;
 	worktree->is_bare = is_bare;
-	worktree->head_ref = NULL;
 	worktree->is_detached = is_detached;
-	worktree->is_current = 0;
 	add_head_info(&head_ref, worktree);
-	worktree->lock_reason = NULL;
-	worktree->lock_reason_valid = 0;
 
 done:
 	strbuf_release(&path);
@@ -138,16 +133,11 @@ static struct worktree *get_linked_worktree(const char *id)
 	if (parse_ref(path.buf, &head_ref, &is_detached) < 0)
 		goto done;
 
-	worktree = xmalloc(sizeof(struct worktree));
+	worktree = xcalloc(1, sizeof(*worktree));
 	worktree->path = strbuf_detach(&worktree_path, NULL);
 	worktree->id = xstrdup(id);
-	worktree->is_bare = 0;
-	worktree->head_ref = NULL;
 	worktree->is_detached = is_detached;
-	worktree->is_current = 0;
 	add_head_info(&head_ref, worktree);
-	worktree->lock_reason = NULL;
-	worktree->lock_reason_valid = 0;
 
 done:
 	strbuf_release(&path);