[JENKINS-58313] Expose pullrequest source commit hash to pipeline env variables

Some operations on pullrequests (like reporting build statuses or creating reports) require to pass the hash of the pullrequest branch head, as known by the remote system.

When using the branch plugin, Jenkins may create a merge commit between the PR source and target branch. It makes it difficult for a pipeline script to retrieve the original source commit hash.

My suggestion is to add a new environment variable, similar to CHANGE_BRANCH, that would expose this source commit. We could name this variable CHANGE_BRANCH_COMMIT_ID, to make it consistent with existing CHANGE_BRANCH and COMMIT_ID.

See original discussion:

https://groups.google.com/d/topic/jenkinsci-dev/-ojqklsaKbw/discussion

Example of operations requiring the PR head commit hash:

• https://developer.atlassian.com/bitbucket/api/2/reference/resource/repositories/%7Busername%7D/%7Brepo_slug%7D/commit/%7Bnode%7D/statuses/build


• https://developer.atlassian.com/server/bitbucket/how-tos/code-insights/


• https://developer.github.com/v3/repos/statuses/


• https://developer.github.com/v3/checks/runs/#create-a-check-run

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Originally reported by henryju, imported from: Expose pullrequest source commit hash to pipeline env variables

• assignee: henryju
  
• status: Open
  
• priority: Minor
  
• component(s): branch-api-plugin
  
• resolution: Unresolved
  
• votes: 4
  
• watchers: 3
  
• imported: 20251211-141027
  

Raw content of original issue

Some operations on pullrequests (like reporting build statuses or creating reports) require to pass the hash of the pullrequest branch head, as known by the remote system.

When using the branch plugin, Jenkins may create a merge commit between the PR source and target branch. It makes it difficult for a pipeline script to retrieve the original source commit hash.


My suggestion is to add a new environment variable, similar to CHANGE_BRANCH, that would expose this source commit. We could name this variable CHANGE_BRANCH_COMMIT_ID, to make it consistent with existing CHANGE_BRANCH and COMMIT_ID.


See original discussion:

https://groups.google.com/d/topic/jenkinsci-dev/-ojqklsaKbw/discussion


Example of operations requiring the PR head commit hash:



	
https://developer.atlassian.com/bitbucket/api/2/reference/resource/repositories/%7Busername%7D/%7Brepo_slug%7D/commit/%7Bnode%7D/statuses/build

	
https://developer.atlassian.com/server/bitbucket/how-tos/code-insights/

	
https://developer.github.com/v3/repos/statuses/

	
https://developer.github.com/v3/checks/runs/#create-a-check-run

• environment: GitHub, Bitbucket

The issue names no source file or test; start by locating the branch-api-plugin code and tests that expose existing CHANGE_BRANCH and COMMIT_ID pipeline environment variables. Trace how pull request source metadata is provided, then add the proposed source commit variable and verify it for pull request builds.

Written by the indexing model from the issue text.