Fails when a package is called in twice with the same patch

[kdebisschop]

Given a structure like this:

Top Level
  Pacakge 1
    Subpackage A
    Subpackage B
        Patch
    Subpackage C
  Package 2
     Subpackage B
        Patch
     Subpackage D

The patch will get queued twice and on the second application will fail. You can also see this if you apply the same patch URL with a different description in one file:

{
  "name": "cweagans/composer-patches-test-project",
  "description": "Project for use in cweagans/composer-patches acceptance tests.",
  "type": "project",
  "license": "BSD-2-Clause",
  "repositories": [
    {
      "type": "path",
      "url": "../composer-patches"
    }
  ],
  "require": {
    "cweagans/composer-patches": "*@dev",
    "drupal/drupal": "~8.2"
  },
  "extra": {
    "patches": {
      "drupal/drupal": {
        "Add a startup config for the PHP web server": "https://www.drupal.org/files/issues/add_a_startup-1543858-58.patch",
        "Add a startup config for the PHP web server again": "https://www.drupal.org/files/issues/add_a_startup-1543858-58.patch"
      }
    }
  }
}

I think if the same patch URL is presented twice, it should only be applied the first time.

[cweagans]

I'm not sure how the patch would get queued twice. The package is only installed once.

In #93 (2.0.0), we'll dedupe patches based on a sha1 hash of the file. I don't plan to do anything about this in 1.x.