OE uses D as the offline install directory in its scripts, not PKG_ROOT.

Upstream-Status: Inappropriate [OE specific usage]

RP 2011/12/15

Index: trunk/libopkg/pkg.c
===================================================================
--- trunk.orig/libopkg/pkg.c	2011-12-15 15:58:39.000000000 +0000
+++ trunk/libopkg/pkg.c	2011-12-15 20:04:50.109992736 +0000
@@ -1280,7 +1280,7 @@
 
      opkg_msg(INFO, "Running script %s.\n", path);
 
-     setenv("PKG_ROOT",
+     setenv("D",
 	    pkg->dest ? pkg->dest->root_dir : conf->default_dest->root_dir, 1);
 
      if (! file_exists(path)) {