Propel ORM：更改diff和migrate的连接设置

So I'm currently developing a little project using Propel ORM (v2.00-dev), and I figured I'd try using Vagrant for the first time.

I've set up the vagrant server to allow external MySQL connections, and built the following config file, so I don't have to ssh into the server every time I want to run propel from the command line

{
  "propel": {
      "paths": {
        "outputDir": "./propel/",
        "phpDir": "./propel/model/",
        "sqlDir": "./propel/sql",
        "phpConfDir": "./propel/conf"
      },
      "database": {
        "connections": {
          "project-local": {
            "adapter": "mysql",
            "dsn": "mysql:host=localhost;dbname=scotchbox",
            "user": "root",
            "password": "root",
            "attributes": []
          },
          "project-remote": {
            "adapter": "mysql",
            "dsn": "mysql:host=192.168.33.10;dbname=scotchbox",
            "user": "root",
            "password": "root",
            "attributes": []
          }
        }
      },
      "runtime": {
        "defaultConnection": "project-local",
        "connections": ["projeect-local","project-remote"]
      },
      "generator": {
        "defaultConnection": "project-remote",
        "connections": ["project-remote","project-local"]
      }
    }
  }

paired with a schema.xml like:

<database name="project-remote">
    <!-- lots of tables in here -->
</database>

Now this has been working great so far. The application runs using project-local, and when I run propel from the command line it switches to project-remote as expected.

When I try and run propel diff however, I get the following error:

[PDOException]
SQLSTATE[HY000] [1045] Access denied for user 'root'@'localhost' (using password: YES)

This suggests that when running diffs, Propel is trying to use the runtime connection settings rather than the generator ones. Is there a way I can change this? I've checked the configuration docs, and I cant see anything about setting a connection.

I've also noticed that the diff command has a --connection argument, but I can't find any info on it, nor can I work out how to use it. I've tried:

propel diff --connection=project-remote

and

propel diff --connection="project-remote"

Both of which result in the following error

[Symfony\Component\Config\Definition\Exception\InvalidConfigurationException]
The path "propel.database.connections..adapter" cannot contain an empty value, but got "".

So, does anyone have any ideas on how to specify a connection for propel diff (and probably migrate)?