amazon-image: fix image.extension value for vpc/vhd files

vpc files use the extension "vhd". `make-disk-image-nix` contains a
lookup table, but does not expose that. vpc is the only format
supported by the amazon image which is affected. Format and extension
are the same for raw and qcow2.

phaer 8cbc6d6d a82b5727

Changed files
+1 -1
nixos
maintainers
scripts
+1 -1
nixos/maintainers/scripts/ec2/amazon-image.nix
···
config.system.nixos.tags = [ "amazon" ];
config.system.build.image = config.system.build.amazonImage;
-
config.image.extension = cfg.format;
+
config.image.extension = if cfg.format == "vpc" then "vhd" else cfg.format;
config.system.build.amazonImage =
let