Allows patch-level to be specified per-project.

- Backport to `1.x`
- Reroll of cweagans#101
- Fixes cweagans#43

src/Plugin/Patches.php

@@ -350,7 +350,7 @@ public function postInstall(PackageEvent $event)
                   $patch->url = $providing_install_path.'/'.$patch->url;
                 }
 
-                $this->getAndApplyPatch($downloader, $install_path, $patch->url);
+                $this->getAndApplyPatch($downloader, $install_path, $patch->url, $package);
                 $this->eventDispatcher->dispatch(
                     null,
                     new PatchEvent(PatchEvents::POST_PATCH_APPLY, $package, $patch->url, $patch->description)
@@ -396,9 +396,10 @@ protected function getPackageFromOperation(OperationInterface $operation)
      * @param RemoteFilesystem $downloader
      * @param $install_path
      * @param $patch_url
+     * @param PackageInterface $package
      * @throws \Exception
      */
-    protected function getAndApplyPatch(RemoteFilesystem $downloader, $install_path, $patch_url)
+    protected function getAndApplyPatch(RemoteFilesystem $downloader, $install_path, $patch_url, PackageInterface $package)
     {
 
         // Local patch file.
@@ -418,6 +419,11 @@ protected function getAndApplyPatch(RemoteFilesystem $downloader, $install_path,
         // it might be useful. p4 is useful for Magento 2 patches
         $patch_levels = $this->getConfig('patch-levels');
 
+        // Check for specified patch level for this package.
+        if (!empty($this->composer->getPackage()->getExtra()['patchLevel'][$package->getName()])){
+            $patch_levels = array($this->composer->getPackage()->getExtra()['patchLevel'][$package->getName()]);
+        }
+
         // Attempt to apply with git apply
         $patched = $this->applyPatchWithGit($install_path, $patch_levels, $filename);