serverless offline bug with env variables

handler.js

"use strict";

const printFoo = (event, context, callback) => {
  const response = {
    statusCode: 200,
    body: JSON.stringify(process.env.FOO)
  };
  callback(null, response);

  // Use this code if you don't use the http event with the LAMBDA-PROXY integration
  // callback(null, { message: 'Go Serverless v1.0! Your function executed successfully!', event });
};

module.exports.foo = printFoo;
module.exports.bar = printFoo;
module.exports.baz = printFoo;

serverless.yml

service: my-service

# You can pin your service to only deploy with a specific Serverless version
# Check out our docs for more details
# frameworkVersion: "=X.X.X"
plugins:
  - serverless-offline

provider:
  name: aws
  runtime: nodejs6.10
  environment:
    FOO: foo

# you can define service wide environment variables here
functions:
  foo:
    handler: handler.foo
    events:
      - http:
          method: get
          path: /foo

  bar:
    handler: handler.bar
    events:
      - http:
          method: get
          path: /bar
    environment:
      FOO: bar

  baz:
    handler: handler.baz
    events:
      - http:
          method: get
          path: /baz
    environment:
      FOO: baz

test.sh

curl 'http://localhost:3000/foo'
curl 'http://localhost:3000/bar'
curl 'http://localhost:3000/baz'

should print

$ sh test.sh
"foo""bar""baz"

dherault/serverless-offline#254