Change zone used by case test. Because instances are now cached by Timezone, this was causing a problem with test_get_valid_1.
Change zone used by case test. Because instances are now cached by Timezone, this was causing a problem with test_get_valid_1.

git-svn-id: f5927daa5f457e40ee4ba532b77e716d68680ae3@51 6a820049-d607-0410-8d0c-bb5410e29337

osheroff/tzinfo