Add a test-case for #12990 (#15072)

* closes #12990
* Add a test-case for #12990

tests/arc/amodule.nim

@@ -1,3 +1,4 @@
+# bug #14219
 var vectors = @["a", "b", "c", "d", "e"]
 
 iterator testVectors(): string =
@@ -7,4 +8,14 @@ iterator testVectors(): string =
 var r = ""
 for item in testVectors():
   r.add item
-echo r
+echo r
+
+# bug #12990
+iterator test(): int {.closure.} =
+  yield 0
+
+let x = test
+while true:
+  let val = x()
+  if finished(x): break
+  echo val

tests/arc/tamodule.nim

@@ -1,5 +1,8 @@
 discard """
-  output: "abcde"
+  output: '''
+abcde
+0
+'''
   cmd: "nim c --gc:arc $file"
 """