Bug #409403: Signal an error if the distribution's metadata has no version
diff --git a/Lib/distutils/dist.py b/Lib/distutils/dist.py
index 41d5dbb..6bda869 100644
--- a/Lib/distutils/dist.py
+++ b/Lib/distutils/dist.py
@@ -206,6 +206,10 @@
                     raise DistutilsSetupError, \
                           "invalid distribution option '%s'" % key
 
+        if self.metadata.version is None:
+            raise DistutilsSetupError, \
+                  "No version number specified for distribution"
+        
     # __init__ ()