--TEST--
Circular dependencies errors uses helpful message
--COMPOSER--
{
    "name": "root/pkg",
    "version": "dev-master",
    "require": {
        "requires/root": "1.0.0"
    },
    "repositories": [
        {
            "type": "package",
            "package": [
                {
                    "name": "requires/root",
                    "version": "1.0.0",
                    "source": { "reference": "some.branch", "type": "git", "url": "" },
                    "require": {
                        "root/pkg": "^1.0"
                    }
                },
                {
                    "name": "root/pkg",
                    "version": "1.0.0"
                }
            ]
        }
    ]
}
--RUN--
update -v

--EXPECT-EXIT-CODE--
2

--EXPECT-OUTPUT--
Loading composer repositories with package information
Updating dependencies
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Root composer.json requires requires/root 1.0.0 -> satisfiable by requires/root[1.0.0].
    - requires/root 1.0.0 requires root/pkg ^1.0 -> satisfiable by root/pkg[1.0.0] from package repo (defining 2 packages) but root/pkg is the root package and cannot be modified. See https://getcomposer.org/dep-on-root for details and assistance.

--EXPECT--