Determines how merge requests are discovered:
Merging the merge request with the current target branch revision
Discover each merge request once with the discovered revision corresponding to the result of merging with the current revision of the target branch
The current merge request revision
Discover each merge request once with the discovered revision corresponding to the merge request head revision without merging
Both the current merge request revision and the merge request merged with the current target branch revision
Discover each merge request twice. The first discovered revision corresponds to the result of merging with the current revision of the target branch in each scan. The second parallel discovered revision corresponds to the merge request head revision without merging