Many ClearCase installations have a trigger that fires on a canceled checkout (uncheckout)
event, that destroys empty branches. If this option is enabled, Jenkins will filter out
such events (example 'Destroy sub-branch "BRANCH_NAME" of branch') from the
poll and change logs. This means that a new build will not be triggered if a developer
cancels a checkout on a file that has not been versioned in the current branch.
If not enable, Jenkins will trigger a new build anytime a developer cancels a checkout.
There are disadvantages by enabling this option as it will not trigger a build when someone removes a branch. For the full discussion thread about this issue please see http://www.nabble.com/ClearCase-build-triggering-td17507838i20.html.