Steps to reproduce

I believe this change: f173ec7#diff-5036eb99239f9418c0458f2a2ec4f496R228
introduced a regression whereby RAILS_ENV=test is added as an argument to the generator. This is only apparent if the generator uses arguments. One generator that does so is the devise generator. See heartcombo/devise#5007

Expected behavior

It should not pass RAILS_ENV as an argument to the generator

Actual behavior

it is passing RAILS_ENV as an agrument

System configuration

Rails version: 6.0.0.beta1

Ruby version: 2.6.0