The comment in the code include the followings:
// Since there is no easy way of knowing whether
MAPREDUCE-1597 is present in the tree or not,
// we use a configuration variable for the same
This is clearly misunderstanding.
MAPREDUCE-1597 is a bug that was fixed for new api (mapreduce package), while CombineHiveInputFormat is using old API (deprecated mapred package). CombineHiveInputFormat does not properly works with any non-splittable compressed file, if that files is written over multiple hdfs partitions (same as CombineFileInputFormat from mapred package, while CombineFileInputFormat from new mapreduce package works beautifully).
Not sure why this issue is marked as closed.