Fix a problem with a slice and splitted numpy
Fix a problem with a slice and splitted numpy

    * Simplify the comes_from_split method
    * Check that if we are in a getitem, a slice is used, and we come from an
      split, we just return the slice (no need to adapt anything)

bsc-dd/hecuba,bsc-dd/hecuba,bsc-dd/hecuba,bsc-dd/hecuba