run_compute on disabled dataset uses pblum_method='absolute'

[kecnry]

Running a forward model on a dataset that is disabled by passing dataset to run_compute ignores options for passband luminosity scaling (and possibly other dataset options - check for third light, irradiation, etc) and for passband luminosity scaling defaults to absolute. For more context, see #986

import phoebe
b = phoebe.default_binary()
b.add_dataset('lc', compute_phases=[0.25], dataset='lc01')
b.set_value('pblum_mode', 'absolute')
b.run_compute(model='enabled_absolute')
b.set_value('pblum_mode', 'component-coupled')
b.run_compute(model='enabled_cc')
b.disable_dataset('lc01')
b.run_compute(dataset='lc01', model='disabled_cc')
print(b.filter(qualifier='fluxes', context='model'))

ParameterSet: 3 parameters
R   fluxes@enabled_absolute@model: [8.70985138e+24] W / m2
R         fluxes@enabled_cc@model: [2.00783523] W / m2
R        fluxes@disabled_cc@model: [8.70985138e+24] W / m2

I don’t remember if passing dataset was an intended feature or not. I know that passing times was intended.
So we’ll need to check if it is and:

• if so: it should still adhere to all dataset parameters (and so match the component-coupled result)
• if not: passing anything to dataset should probably be caught immediately and raise an error.