added src_version cache

__init__.py

@@ -52,6 +52,7 @@ def __src_version__():
     #
 
 
+    if not hasattr(__src_version__, 'rval'):
         #print 'name:', __name__
         location = _imp.find_module(__name__)[1]
         #print 'location:', location
@@ -80,5 +81,7 @@ def __src_version__():
         if len(tokens) == 2:
             assert tokens[1] == 'tip\n'
 
-    return tokens[0]
+        __src_version__.rval = tokens[0]
+
+    return __src_version__.rval