Fix local exec

Execute as module, with globals (which are also locals)
https://docs.python.org/3/library/functions.html#exec

Author: hermansje

pythonwhat/local.py

@@ -7,14 +7,14 @@
 from contextlib import redirect_stdout
 
 class StubShell(object):
-    
+
     def __init__(self, init_code = None):
         self.user_ns = {}
         if init_code:
             self.run_code(init_code)
-            
+
     def run_code(self, code):
-        exec(code, None, self.user_ns)
+        exec(code, self.user_ns)
 
 class StubProcess(object):