Couldn't find any revision to build When sourceBranch does not exist upstream

[rahilb]

When I send a pull request from my fork f, branch b1, to the origin repo o branch master, the pull request fails (i think) as b1 does not exist in o.

[EnvInject] - Loading node environment variables.
Building in workspace /Users/server/.jenkins/jobs/PR Builder/workspace
 > git rev-parse --is-inside-work-tree # timeout=10
Fetching changes from the remote Git repository
 > git config remote.origin.url ssh://git@... # timeout=10
Fetching upstream changes from ssh://git@...
 > git --version # timeout=10
using GIT_SSH to set credentials ci-user ssh key
 > git -c core.askpass=true fetch --tags --progress ssh://git@... +refs/pull-requests/*:refs/remotes/origin/pr/*
 > git rev-parse refs/remotes/origin/b1^{commit} # timeout=10
 > git rev-parse refs/remotes/origin/origin/b1^{commit} # timeout=10
 > git rev-parse origin/b1^{commit} # timeout=10
ERROR: Couldn't find any revision to build. Verify the repository and branch configuration for this job.
Notified Stash for commit with id d31ee53bc4cc0dc74aa01e2932d1533d64958947
Finished: FAILURE

[nickbroon]

If you follow the steps in the updated README.md should should avoid this issue.

[nemccarthy]

This should work in 1.5