We had issues building python 2.7 on hppa-hp-hpux machines because sysconfig and distutils had different ideas of the platform name.

./python -c 'import os, sys; from distutils.util import get_platform as plat1; from sysconfig import get_platform as plat2; print plat1();print plat2()'
hp-ux-B.11.11-9000_785
hp-ux-B.11.11-9000-785

Notice that one has an underscore, the other a dash.

Either the code is sysconfig or distutils needs to change slightly so that they match.
e.g.
Index: Lib/sysconfig.py
===================================================================
--- Lib/sysconfig.py.orig       2010-05-19 22:20:14.000000000 +0000
+++ Lib/sysconfig.py    2010-07-16 02:52:39.385322407 +0000
@@ -569,3 +569,3 @@
     machine = machine.replace(' ', '_')
-    machine = machine.replace('/', '-')
+    machine = machine.replace('/', '_')