Index: boost_1_45_0/tools/build/v2/tools/python.jam
===================================================================
--- boost_1_45_0.orig/tools/build/v2/tools/python.jam	2010-12-27 16:10:56.340207790 -0500
+++ boost_1_45_0/tools/build/v2/tools/python.jam	2010-12-27 16:11:53.751709203 -0500
@@ -806,11 +806,7 @@
     }
 
     # Anything left to compute?
-    if $(includes) && $(libraries)
-    {
-        .configured = true ;
-    }
-    else
+    if ! $(includes) || ! $(libraries)
     {
         version ?= $(fallback-version) ;
         version ?= 2.5 ;
@@ -818,6 +814,11 @@
         compute-default-paths $(target-os) : $(version) : $(prefix:E=) ;
     }
 
+    if $(includes) && $(libraries)
+    {
+        .configured = true ;
+    }
+
     if ! $(interpreter-cmd)
     {
         fallback-cmd ?= python ;