Autoload dev packages as well for script execution, refs #1430

src/Composer/Script/EventDispatcher.php

@@ -140,7 +140,10 @@ class EventDispatcher
         }
 
         $generator = new AutoloadGenerator;
-        $packages = $this->composer->getRepositoryManager()->getLocalRepository()->getPackages();
+        $packages = array_merge(
+            $this->composer->getRepositoryManager()->getLocalRepository()->getPackages(),
+            $this->composer->getRepositoryManager()->getLocalDevRepository()->getPackages()
+        );
         $packageMap = $generator->buildPackageMap($this->composer->getInstallationManager(), $package, $packages);
         $map = $generator->parseAutoloads($packageMap, $package);
         $this->loader = $generator->createLoader($map);