Does 'master' exist?

[scottstav]

it does not...

Switched to a new branch 'update-from-master-f6a2b77-rebase-strategy-ours'
⛔ gitmux execution failed.
⏩ Error at line 574.
fatal: invalid upstream 'destination/master'
Invalid upstream. Does 'master' exist in 'https://github.com/scottstav/scotty-api'?
⛔ gitmux execution failed.