print errno when reporting a system call error

diff --git a/worktree.c b/worktree.c
index fa7bc67a50a6d52116b0ca994b473668998f1c3f..bae787cf8d7e968e8d5118bf54f17112c0229bf5 100644 (file)
--- a/worktree.c
+++ b/worktree.c
@@ -250,16 +250,19 @@ struct worktree *find_worktree(struct worktree **list,
 {
        struct worktree *wt;
        char *path;
+       char *to_free = NULL;
 
        if ((wt = find_worktree_by_suffix(list, arg)))
                return wt;
 
-       arg = prefix_filename(prefix, strlen(prefix), arg);
+       if (prefix)
+               arg = to_free = prefix_filename(prefix, arg);
        path = real_pathdup(arg, 1);
        for (; *list; list++)
                if (!fspathcmp(path, real_path((*list)->path)))
                        break;
        free(path);
+       free(to_free);
        return *list;
 }