Remove excess subtasks

[wd15]

Just using this workflow creates way more subtasks then is necessary,

x_data1 = PrimitiveTransformer(n_state=2, min_=0.0, max_=1.0).fit(x_data).transform(x_data)
correlations = TwoPointCorrelation(periodic_boundary=True, cutoff=21, correlations=[(0,0),(1,1)])
x_data2 = correlations.fit(x_data1).transform(x_data1)
x_data2.chunks
x_data2.visualize()

If x_data.chunks is ((200, 200, 200, 200, 200, 200), (21,), (21,)) it creates 22 parallel subtasks in the graph. Something is very wrong.