make tests green again

tests/notnil/tnotnil1.nim

@@ -1,6 +1,6 @@
 discard """
   errormsg: "'y' is provably nil"
-  line:38
+  line:25
 """
 
 import strutils
@@ -10,19 +10,6 @@ type
   TObj = object
     x, y: int
 
-type
-  superstring = string not nil
-
-
-proc q(s: superstring) =
-  echo s
-
-proc p2() =
-  var a: string = "I am not nil"
-  q(a) # but this should and does not
-
-p2()
-
 proc q(x: pointer not nil) =
   discard