"Upstream already exists" error when creating a fork

[billygriffin]

Describe the bug

We're seeing an error that the upstream remote already exists when creating a fork, even though the fork is created properly.

Version & OS

GitHub Desktop 2.3

Steps to reproduce the behavior

Fork creation flow when you've cloned a repo you don't have write access to.

Expected behavior

Create the fork with no errors.

Actual behavior

See error that the upstream remote already exists.