Can't set Content-Type header

[JurajKavka]

Hi

I'm trying to set Content-Type hedaer but it doesn't work and still I have application/json; charset=utf-8 in responses. I'm trying to send pdf document to user like

ctx.response.set('Content-Type', meta.mimetype || 'application/octet-stream');
ctx.response.set('Content-Disposition', `inline; filename="${meta.name}"`);
await send(ctx, file, {
  root: '/',
});

Also using seatHeader option does not work. I found this issue koajs/koa#1120 but I'm not sure if it is related...

Thank You.