set_x adapt assertion

[MUCDK]

pd.testing.assert_series_equal(self.adata_src.[obs_names.to](http://obs_names.to/)_series(), [data.columns.to](http://data.columns.to/)_series())

requires me to do

early_dist.index.name = 'cell'
late_dist.index.name = 'cell'
early_dist.columns.name = 'cell'
late_dist.columns.name = 'cell'

which is a bit on an overkill I think