t1006: assert error output of cat-file

Test "cat-file $arg1 $arg2 error on missing full OID" in
t1006-cat-file.sh compares files "expect.err" and "err.actual" to assert
the expected error output of "git cat-file".  A similar test in the same
file named "cat-file $arg1 $arg2 error on missing short OID" also
creates these two files, but doesn't use them in assertions.

Assert error output of "git cat-file" in test "cat-file $arg1 $arg2
error on missing short OID" of t1006-cat-file.sh to improve test
coverage.

Signed-off-by: Andrei Rybak <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: rybak

t/t1006-cat-file.sh

@@ -603,7 +603,8 @@ do
 			fatal: Not a valid object name $(test_oid deadbeef_short)
 			EOF
 			test_must_fail git cat-file $arg1 $arg2 $(test_oid deadbeef_short) >out 2>err.actual &&
-			test_must_be_empty out
+			test_must_be_empty out &&
+			test_cmp expect.err err.actual
 		'
 
 		test_expect_success "cat-file $arg1 $arg2 error on missing full OID" '