Multi-user git

Modify your ~/.ssh/config file as such to seamlessly utilize multiple git users on the same machine

Host user1
  Hostname github.com
  User git
  IdentityFile ~/.ssh/username1_pubkey
  IdentitiesOnly yes

Host user2
  Hostname github.com
  User git
  IdentityFile ~/.ssh/username2_pubkey
  IdentitiesOnly yes

Then for your repo ensure git remote -v is of the form

[email protected]:<username1>/<username1-repo>.git

Of course, ensure your ssh key is added to the respective repo.