Changes to avoid unnecessary assumptions

router/assumptions.gobra

@@ -39,6 +39,12 @@ ensures malformedPath.ErrorMem()
 decreases _
 func establishMemMalformedPath()
 
+ghost
+ensures alreadySet != nil
+ensures alreadySet.ErrorMem()
+decreases _
+func establishAlreadySet()
+
 ghost
 ensures unsupportedPathTypeNextHeader.ErrorMem()
 decreases _