windres handles #include suffixes?

[Alon Bar-Lev]

Hello,

I have the following example:

master.rc
---
#include <winresrc.h>
#include "slave1.rc"
#include "slave2.rc.h"
---

slave1.rc
---
STRINGTABLE
LANGUAGE LANG_ENGLISH, SUBLANG_NEUTRAL
BEGIN
1 "SLAVE1"
END
---

slave2.rc
---
STRINGTABLE
LANGUAGE LANG_ENGLISH, SUBLANG_NEUTRAL
BEGIN
2 "SLAVE2"
END
---

Output is:
---
LANGUAGE 9, 0

STRINGTABLE MOVEABLE PURE DISCARDABLE
BEGIN
  1, "SLAVE1"
END
---

Where did slave2 content gone?
How come windres handles preprocessor output differently?
If I rename slave2.rc.h to slave2.rc it works.

Is this by design? If it is, what is the reason?

Thanks!
Alon.