t5530: check protocol response for "not our ref"

t5530: check protocol response for "not our ref"

Back in 9f9aa76130 (upload-pack: Improve error message when bad ref
requested, 2010-07-31), we added a test to make sure that we die with a
sensible message when the client asks for an object we don't have.

Much later, in bdb31eada7 (upload-pack: report "not our ref" to client,
2017-02-23), we started reporting that information via an "ERR" line in
the protocol. Let's check that part, as well.

While we're touching this test, let's drop the "-q" on the grep calls.
Our usual test style just relies on --verbose to control output.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>