[JENKINS-22974] - Added a test case for the issue

Signed-off-by: Oleg Nenashev <o.v.nenashev@gmail.com>
[FIXED JENKINS-22974] - Check for non-existent upstream builds

Signed-off-by: Oleg Nenashev <o.v.nenashev@gmail.com>
Merge pull request #4 from synopsys-arc-oss/JENKINS_22974_NPE_in_makeUserVars

[FIXED JENKINS-22974] - NPE in makeUserVars if an upstream build is missing