Add reinstall python before layman -a calculate.

pym/cl_assemble.py

@@ -605,6 +605,10 @@ class cl_assemble(color_print):
         self.printMessageForTest(_("Installing %s")%"layman")
         self.runChroot(emergeLayman)
 
+        emergePython = "USE='xml' emerge python:2.7"
+        self.printMessageForTest(_("Installing %s")%"python")
+        self.runChroot(emergePython)
+
         self.printMessageForTest(_("Loading calculate overlay"))
         if filter(lambda x:"calculate" in x,self.runChroot("layman -l")):
             self.runChroot("layman -s calculate")