Source branch is not deleted during automatic merge of a pull request with build checks passed

Issue Summary

Source branch is not deleted during automatic merge of a pull request with all the build checks passed

Steps to Reproduce

1. Create a new branch and make some change
2. Make a PR from the newly created branch to the master. enable "source branch deletion".
3. Click on the merge button as soon as you create the PR, notice the information in the PR merge you get
4. You will observe that Pull request gets merged as soon as the build on the PR become successful

Expected Results

After the pull request is merged, the source branch should get deleted.

Actual Results

The source branch shown in the list of Active Branches.

Workaround

Manually merge PR so that source branch gets deleted. In case of automatic merge, user need to delete the source branch manually.