The verify-tag command supports multiple tag names to verify, but
existing tests only test for invocation with a single tag.
Add a test invoking it with multiple tags.
Helped-by: Jeff King <peff@peff.net> Signed-off-by: Santiago Torres <santiago@nyu.edu> Reviewed-by: Eric Sunshine <sunshine@sunshineco.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>