fix modify() field deletion when field isn't already there

ngsrinivas · ngsrinivas · commit b302f3defeea · 2014-01-19T14:40:09.000-08:00
diff --git a/pyretic/core/util.py b/pyretic/core/util.py
@@ -73,7 +73,8 @@ def update(self, new_dict=None, **kwargs):
     def remove(self, ks):
         d = self._dict.copy()
         for k in ks:
-            del d[k]
+            if k in d:
+                del d[k]
         return self.__class__(d)
         
     def pop(self, *ks):
