Fix $PATH and add $PYTHONPATH used to run regen.
diff --git a/Makefile.in b/Makefile.in
index 57dad87..cb92728 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -261,7 +261,8 @@
 $(srcdir)/Lib/$(MACHDEP):
 		mkdir $(srcdir)/Lib/$(MACHDEP)
 		cp $(srcdir)/Lib/generic/regen $(srcdir)/Lib/$(MACHDEP)/regen
-		export PATH; PATH="`pwd`:$PATH"; \
+		export PATH; PATH="`pwd`:$(PATH)"; \
+		export PYTHONPATH; PYTHONPATH="`pwd`/Lib"; \
 		cd $(srcdir)/Lib/$(MACHDEP); ./regen
 
 # Install the include files