I have a jenkins job that runs when code is pushed to `master` and `develop` branch. This job also picks up PRs. This job also has `sha1` as a build parameter to trigger builds manually.

The job picks up PRs and builds them. Same with pushes to `master` or `develop`. The issue is when The job is triggered manually. It seems to pickup a random branch. sometimes a PR, sometimes `origin/develop`. The GIT_BRANCH environment variable is overwritten with some other branch and not sha1.

*Job config*
````
build parameters: sha1 (default value: origin/<branchName>) so technically, the job should fail as there is no branch called `origin/<branchName>`
Branches to build -1 : origin/master
Branches to build - 2: origin/develop
Branches to build - 3: ${sha1}
Refspec: +refs/heads/*:refs/remotes/origin/* +refs/pull/*:refs/remotes/origin/pr/*

• [√ ] Build when a change is pushed to GitHub
• [√ ] GitHub Pull Request Builder
  ````

*Jenkins and plugin versions*
````
jenkins version: 2.7.1

Git client plugin: 2.0.0
Git plugin: 3.0.0
GitHub API Plugin: 1.77
GitHub plugin: 1.21.1
GitHub Pull Request Builder: 1.33.1
````