t8005: avoid grep on non-ASCII data

t8005: avoid grep on non-ASCII data

GNU grep 2.23 detects the input used in this test as binary data so it
does not work for extracting lines from a file.  We could add the "-a"
option to force grep to treat the input as text, but not all
implementations support that.  Instead, use sed to extract the desired
lines since it will always treat its input as text.

While touching these lines, modernize the test style to avoid hiding the
exit status of "git blame" and remove a space following a redirection
operator.  Also swap the order of the expected and actual output
files given to test_cmp; we compare expect and actual to show how
actual output differs from what is expected.

Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>