Merge branch 'rs/range-diff-avoid-segfault-with-I'

"git range-diff -I... <range> <range>" segfaulted, which has been
corrected.

* rs/range-diff-avoid-segfault-with-I:
  range-diff: avoid segfault with -I

range-diff.c

@@ -482,6 +482,7 @@ static void output(struct string_list *a, struct string_list *b,
 	else
 		diff_setup(&opts);
 
+	opts.no_free = 1;
 	if (!opts.output_format)
 		opts.output_format = DIFF_FORMAT_PATCH;
 	opts.flags.suppress_diff_headers = 1;
@@ -542,6 +543,8 @@ static void output(struct string_list *a, struct string_list *b,
 	strbuf_release(&buf);
 	strbuf_release(&dashes);
 	strbuf_release(&indent);
+	opts.no_free = 0;
+	diff_free(&opts);
 }
 
 int show_range_diff(const char *range1, const char *range2,