Don't disconnect sender on cancellation (#958)
Don't disconnect sender on cancellation (#958)

This was causing a "race condition" where the sender would
be disconnected after cancellation when another was created.

LonamiWebs/Telethon,expectocode/Telethon,LonamiWebs/Telethon,LonamiWebs/Telethon,LonamiWebs/Telethon