Its inclusion placed where it is, it affects the hypervisor build as well.
The hypervisor build, in its _install rule, uses $(DEBUG_DIR), first in

	[ -d "$(D)$(DEBUG_DIR)" ] || $(INSTALL_DIR) $(D)$(DEBUG_DIR)

$(D) is an absolute directory (shorthand for $(DESTDIR)). $(DEBUG_DIR) as
set by Paths.mk is, too. Both point into the build tree. The two simply
shouldn't be glued together.

Note that the earlier

	[ -d $(D)$(BOOT_DIR) ] || $(INSTALL_DIR) $(D)$(BOOT_DIR)

continues to be working fine, as BOOT_DIR continues to be controlled by
config/StdGNU.mk. Its DEBUG_DIR isn't taking effect anymore, when for the
hypervisor build it should.

And of course behavior now differs between building xen/ in a tree where
tools/ was built before vs in an otherwise clean tree.

Fixes: 82b9cc04a7c7 ("build: add make macro for making file from file.in")
Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
This is clumsy, but I can't think of anything better. Suggestions anyone?

--- a/Config.mk
+++ b/Config.mk
@@ -162,7 +162,9 @@ endef
 PATH_FILES := Paths.mk
 INC_FILES = $(foreach f, $(PATH_FILES), $(XEN_ROOT)/config/$(f))
 
+ifndef XEN_FULLVERSION
 -include $(INC_FILES)
+endif
 
 BUILD_MAKE_VARS = $(foreach f, $(PATH_FILES), $(shell awk '$$2 == ":=" { print $$1; }' $(XEN_ROOT)/config/$(f).in))