Weird behavior with field replacement and method that uses apply_global_index

[ikrommyd]

This

from coffea.nanoevents import NanoEventsFactory

events = NanoEventsFactory.from_root({"https://github.com/CoffeaTeam/coffea/raw/master/tests/samples/nano_dy.root": "Events"}).events()
events["Photon", "eta_to_use"] = events.Photon.eta
events["Electron", "eta_to_use"] = events.Electron.eta + events.Electron.deltaEtaSC
print(events.Photon.matched_electron.eta_to_use.compute()[-10:])

events = NanoEventsFactory.from_root({"https://github.com/CoffeaTeam/coffea/raw/master/tests/samples/nano_dy.root": "Events"}).events()
events["Photon", "eta_to_use"] = events.Photon.eta
events["Electron", "eta_to_use"] = events.Electron.eta
print(events.Photon.matched_electron.eta_to_use.compute()[-10:])

incorrectly prints

[[], [0.776], [], [2.02], [], [-0.00642], [], [], [], []]
[[], [0.776], [], [2.02], [], [-0.00642], [], [], [], []]

while the eta_to_use field is different in both cases for electrons. The seemingly redundant events["Photon", "eta_to_use"] = events.Photon.eta is part of the reproducer. If you remove it, it works.
The correct output should be

[[], [0.776], [], [2.02], [], [-0.00642], [], [], [], []]
[[], [0.785], [], [2.02], [], [-0.0595], [], [], [], []]

[ikrommyd]

If you remove the second events reading in the above reproducer and run it like this in a notebook:

from coffea.nanoevents import NanoEventsFactory

events = NanoEventsFactory.from_root({"https://github.com/CoffeaTeam/coffea/raw/master/tests/samples/nano_dy.root": "Events"}).events()
events["Photon", "eta_to_use"] = events.Photon.eta
events["Electron", "eta_to_use"] = events.Electron.eta + events.Electron.deltaEtaSC
print(events.Photon.matched_electron.eta_to_use.compute()[-10:])

events["Photon", "eta_to_use"] = events.Photon.eta
events["Electron", "eta_to_use"] = events.Electron.eta
print(events.Photon.matched_electron.eta_to_use.compute()[-10:])

You will get the correct output the first time you run the cell

[[], [0.776], [], [2.02], [], [-0.00642], [], [], [], []]
[[], [0.785], [], [2.02], [], [-0.0595], [], [], [], []]

and all the following times you rerun the same cell you will be getting

[[], [0.785], [], [2.02], [], [-0.0595], [], [], [], []]
[[], [0.785], [], [2.02], [], [-0.0595], [], [], [], []]