Merge branch 'rs/diff-exit-code-binary'

"git diff --exit-code" ignored modified binary files, which has
been corrected.

* rs/diff-exit-code-binary:
  diff: report modified binary files as changes in builtin_diff()

diff.c

@@ -3675,6 +3675,7 @@ static void builtin_diff(const char *name_a,
 			emit_diff_symbol(o, DIFF_SYMBOL_BINARY_FILES,
 					 sb.buf, sb.len, 0);
 			strbuf_release(&sb);
+			o->found_changes = 1;
 			goto free_ab_and_return;
 		}
 		if (fill_mmfile(o->repo, &mf1, one) < 0 ||

t/t4017-diff-retval.sh

@@ -145,6 +145,14 @@ test_expect_success 'option errors are not confused by --exit-code' '
 
 for option in --exit-code --quiet
 do
+	test_expect_success "git diff $option returns 1 for changed binary file" "
+		test_when_finished 'rm -f .gitattributes' &&
+		git reset --hard &&
+		echo a binary >.gitattributes &&
+		echo 2 >>a &&
+		test_expect_code 1 git diff $option
+	"
+
 	test_expect_success "git diff $option returns 1 for copied file" "
 		git reset --hard &&
 		cp a copy &&