Old ubuntu doesn't have dpkg-architecture installed by default

setup.py

@@ -312,8 +312,9 @@ def build_extensions(self):
 
         elif sys.platform.startswith("linux"):
             arch_tp = (plat.processor(), plat.architecture()[0])
-            # This should be correct on debian derivatives.
-            if plat.dist()[0].lower() in ('debian', 'ubuntu'):
+            # This should be correct on debian.
+            # Ubunbu <= Precise fails, >= Trusty succeeds.
+            if plat.dist()[0].lower() == 'debian':
                 # If this doesn't work, don't just silently patch
                 # downstream because it's going to break when people
                 # try to build pillow from source instead of