xcscope don't work with sub-directories

I've read the docs, but still can't make xcscope.el work with sources in sub-directories.

files in the directory:

cscope.out
[...]
got/
lib/

I start emacs got/got.c, then point cursor to the function, which is defined in file inside lib/ directory, and press C-s c d, and I get:

Finding global definition: got_worktree_open
Database directory: /home/misha/work/got/

cscope: no source files found


Search complete.  Search time = 0.02 seconds.

If I patch xcscope.el with the following:

--- xcscope.el.orig     Sun Mar 13 22:34:38 2022
+++ xcscope.el  Sun Mar 13 22:34:47 2022
@@ -2500,7 +2500,7 @@
     (save-excursion
       (catch 'finished
        (set-buffer outbuf)
-       (setq options '("-L"))
+       (setq options '("-LR"))
        (while (and (not done) cscope-search-list)
          (setq next-item (car cscope-search-list)
                cscope-search-list (cdr cscope-search-list)

everything starts working, and I get window with function name, and can jump to file inside lib/ directory.

I can't imagine that I'm first person, who has source files in different sub-directories. Am I missing something obvious?

OS: OpenBSD current
Cscope: cscope-15.9p0

Start in xcscope.el around the search option construction near the cscope-search-list loop, then reproduce the reported lookup with source files in got/ and lib/. Verify that finding a global definition works across sub-directories and that the resulting location can be opened in Emacs.