ControlTreeMixin: Allocation to branches depends on order of ensemble members
Imagine a case with 6 ensemble members. The first one has a timeseries of 1.0, the second one 1.1, etc.
Assuming a binary tree with a single branching point, the ideal allocation would be ensemble member 1-3 in one branch and 4-6 in the second. Currently that is the case, provided the ordering of the ensemble members is as described above.
If we however put ensemble member 3 first in the list, it would pick that one as the reference for one branch, it would pick 6 as reference for the second branch, and then end up with the allocation of 1-4 for the first, and 5-6 for the second branch.