Previously init would crash if given these options:
-backend=false -get-plugins=true
This is because the state is used as a source of provider dependency
information, and we need to instantiate the backend to get the state.
To avoid the crash, we now use the following adjusted behavior:
- if -backend=true, we behave as before
- if -backend=false, we instead try to instantiate the backend the same
way any other command would, without modifying its configuration
- if we're able to instantiate the backend, we use it to fetch state
for dependency resolution purposes
- if the backend is not instantiable then we assume it's not yet
configured and proceed with a nil state, which may cause us to see an
incomplete picture of the dependencies but still allows the install
to succeed. Subsequently running "terraform plan" will not work until
the backend is (re-)initialized, so the incomplete picture of required
plugins is safe.