configfile argument doesn't override if config.yaml exists

[blakeldridge]

Version Checks (indicate both or one)

• [x] I have confirmed this bug exists on the lastest release of PyPSA-Eur.

• [x] I have confirmed this bug exists on the current master branch of PyPSA-Eur.

Issue Description

If you have config/config.yaml present in your workflow, using --configfile in a snakemake command does not override the config.yaml. Instead it will take on the config.yaml values.

I found this issue by accidently having an empty config.yaml file, which lead to the error : "Config file must be given as JSON or YAML with keys at top level"

To reproduce:

• create clean copy of pypsa-eur
• create config.yaml file (leave empty)
• run the command snakemake -call solve_elec_networks --configfile config/config.default.yaml

This should lead to the error above.

This probably means the snakefile could be changed:

if Path("config/config.yaml").exists():

    configfile: "config/config.yaml"

Needs to instead check if an arguement is passed for configfile, otherwise it checks if config.yaml exists

Reproducible Example

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Expected Behavior

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Installed Versions

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