Re: [PATCH 1/8] midx: expose 'write_midx_file_only()' publicly

Taylor Blau [off-list ref] writes:

 	if (ends_with(file_name, ".idx")) {
 		display_progress(ctx->progress, ++ctx->pack_paths_checked);
-		if (ctx->m && midx_contains_pack(ctx->m, file_name))
-			return;
+		if (ctx->m) {
+			if (midx_contains_pack(ctx->m, file_name))
+				return;
+		} else if (ctx->to_include) {
+			if (!string_list_has_string(ctx->to_include, file_name))
+				return;

What's the expected number of elements on the to_include list?  I am
wondering about the performance implications of using linear search
over the string-list, of course.  Is it about the same order of the
number of packfiles in a repository (up to several dozens, or 1000
at most unless you are insane, or something like that)?