Fix #12340 - Reload site to pick up new expressions package

Author: NathanW2

python/user.py

@@ -44,6 +44,9 @@ def load_user_expressions(path):
 if not os.path.exists(initfile):
     open(initfile, "w").close()
 
+import site
+reload(site)
+
 import expressions
 
 expressions.load = load_user_expressions