Empty environment variable and empty yaml key behave differently

[rngadam]

configargparse v1.7

usage

given this add_argument:

        parser.add_argument(
            "--accept-taa",
            type=str,
            nargs=2,
            metavar=("<acceptance-mechanism>", "<taa-version>"),
            env_var="ACAPY_ACCEPT_TAA",
            help=(
                "Specify the acceptance mechanism and taa version for which to accept"
                " the transaction author agreement. If not provided, the TAA must"
                " be accepted through the TTY or the admin API."
            ),
        )

yaml

given this yaml file:

accept-taa: 

value is not set and is ignored

yaml

given this environment variable (loaded with docker --env-file):

ACAPY_ACCEPT_TAA=

exception:

error: argument --accept-taa: expected 2 arguments

expected

empty environment variable same behavior as no value yaml; if value-less and expect a value, just treat it as not specified