If you get following error while you are pushing/pulling changes with Heroku git repository,
ssh_exchange_identification: Connection closed by remote host
It means, your machine is trying to connect ssh over port 443. You can solve this problem by setting default ssh port to 22.In order to do this, open up your ssh config file,
and set "Port" value to 22 and save it. You are done! You can use git operations now.