[Cook] How does c_incl search for included files?

[Gottfried Hegmanns]

I'm testing the following configuration (cook 221):

Repository:
bb/source/hello.c   (this includes hello.h)
bb/includes/hello.h  (this includes hello2.h)
bb/includes/hello2.h (this includes hello3.h)
bb/includes/hello3.h

Sandbox:
work/includes/hello.h
work/includes/hello3.h

If I run the following c_incl command from my sandbox:
c_incl -ns -nc -I. -Iincludes -I../bb/. -I../bb/includes
../bb/source/hello.c

I get the following output:
includes/hello.h
....../bb/includes/hello2.h
....../bb/includes/hello3.h

c_incl correctly finds hello.h in the sandbox, correctly locates hello2.h
in the repository but takes hello3.h also from the repository which is
wrong, should come from the sandbox. It seems files included in includes
are not searched correctly along the -I path given.

Is it a bug or am I doing something wrong?

regards
Gottfried