Imporoved exception message for GitDownloader (various protocols for github)

src/Composer/Downloader/GitDownloader.php

@@ -92,18 +92,20 @@ class GitDownloader extends VcsDownloader
         // github, autoswitch protocols
         if (preg_match('{^(?:https?|git)(://github.com/.*)}', $url, $match)) {
             $protocols = array('git', 'https', 'http');
+            $messages = array();
             foreach ($protocols as $protocol) {
                 $url = $protocol . $match[1];
                 if (0 === $this->process->execute(call_user_func($commandCallable, $url), $handler)) {
                     return;
                 }
+                $messages[] = '- ' . $url . "\n" . preg_replace('#^#m', '  ', $this->process->getErrorOutput());
                 if (null !== $path) {
                     $this->filesystem->removeDirectory($path);
                 }
             }
 
             // failed to checkout, first check git accessibility
-            $this->throwException('Failed to clone ' . $url .' via git, https and http protocols, aborting.' . "\n\n" . $this->process->getErrorOutput(), $url);
+            $this->throwException('Failed to clone ' . $url .' via git, https and http protocols, aborting.' . "\n\n" . implode("\n", $messages), $url);
         }
 
         $command = call_user_func($commandCallable, $url);

tests/Composer/Test/Downloader/GitDownloaderTest.php

@@ -78,19 +78,19 @@ class GitDownloaderTest extends \PHPUnit_Framework_TestCase
             ->will($this->returnValue(1));
 
         $expectedGitCommand = $this->getCmd("git clone 'https://github.com/composer/composer' 'composerPath' && cd 'composerPath' && git checkout 'ref' && git reset --hard 'ref' && git remote add composer 'https://github.com/composer/composer'");
-        $processExecutor->expects($this->at(1))
+        $processExecutor->expects($this->at(2))
             ->method('execute')
             ->with($this->equalTo($expectedGitCommand))
             ->will($this->returnValue(1));
 
         $expectedGitCommand = $this->getCmd("git clone 'http://github.com/composer/composer' 'composerPath' && cd 'composerPath' && git checkout 'ref' && git reset --hard 'ref' && git remote add composer 'http://github.com/composer/composer'");
-        $processExecutor->expects($this->at(2))
+        $processExecutor->expects($this->at(4))
             ->method('execute')
             ->with($this->equalTo($expectedGitCommand))
             ->will($this->returnValue(0));
 
         $expectedGitCommand = $this->getCmd("git remote set-url --push origin 'git@github.com:composer/composer.git'");
-        $processExecutor->expects($this->at(3))
+        $processExecutor->expects($this->at(5))
             ->method('execute')
             ->with($this->equalTo($expectedGitCommand), $this->equalTo(null), $this->equalTo('composerPath'))
             ->will($this->returnValue(0));