Fix #964, fix #1384

Doesn't actually fix those bugs, but they can no longer be reproduced. Test
cases have been added.

tests/stdlib/tunittest.nim

@@ -1,4 +1,20 @@
 import unittest
+
+
+proc doThings(spuds: var int): int =
+  spuds = 24
+  return 99
+test "#964":
+  var spuds = 0
+  check doThings(spuds) == 99
+  check spuds == 24
+
+
+from strutils import toUpper
+test "#1384":
+  check(@["hello", "world"].map(toUpper) == @["HELLO", "WORLD"])
+
+
 import options
 test "unittest typedescs":
   check(none(int) == none(int))