This is a follow-up to JENKINS-14276. I'm creating this to better track the issues I fixed in my original pull-request [1], which I will update accordingly.

To reproduce:

• A parametrized build with parameter BRANCH_TO_BUILD, with default value "branch1"
• Git SCM with branch specifier "${BRANCH_TO_BUILD}"
• SCM polling enabled
• Previous manual job launch with BRANCH_TO_BUILD=branch2

Expected:

• When polling, BRANCH_TO_BUILD is set to branch1 (default value), so only updates to branch1 trigger a build.

Actual:

• When polling, BRANCH_TO_BUILD is set to branch2 (value from last execution).

[1] https://github.com/jenkinsci/git-plugin/pull/293