t0002: simplify error checking
This ancient test script does a lot of manual checking of
test conditions with "if" blocks. We can simplify this
by relying on helpers like test_must_fail.
Note that a failing "grep" call here won't produce any
verbose output, but that's OK. These days we rely on "-x" to
tell us about such commands. And in addition, these greps
are soon to be converted to test_i18ngrep (which is itself
soon learning to be more verbose).
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>