*/
public RevCommit getBaseCommit(final int aIdx, final int bIdx)
throws IncorrectObjectTypeException,
IOException {
if (sourceCommits[aIdx] == null)
throw new IncorrectObjectTypeException(sourceObjects[aIdx],
Constants.TYPE_COMMIT);
if (sourceCommits[bIdx] == null)
throw new IncorrectObjectTypeException(sourceObjects[bIdx],
Constants.TYPE_COMMIT);
walk.reset();
walk.setRevFilter(RevFilter.MERGE_BASE);
walk.markStart(sourceCommits[aIdx]);
walk.markStart(sourceCommits[bIdx]);