Merge remote-tracking branch 'Nami-Doc/patch-1'

src/Composer/Downloader/GitDownloader.php

@@ -93,7 +93,14 @@ class GitDownloader extends VcsDownloader
                     $this->filesystem->removeDirectory($path);
                 }
             }
-            throw new \RuntimeException('Failed to checkout ' . $url .' via git, https and http protocols, aborting.' . "\n\n" . $this->process->getErrorOutput());
+            
+            // failed to checkout, first check git accessibility
+            $output = $this->process->getErrorOutput();
+            if (127 === $this->process->execute('git --version', $handler)) {
+                throw new \RuntimeException('Failed to checkout ' . $url . ' via git, it isn\'t accessible through the console, please check your installation and your PATH env.' . "\n\n" . $this->process->getErrorOutput());
+            }
+
+            throw new \RuntimeException('Failed to checkout ' . $url .' via git, https and http protocols, aborting.' . "\n\n" . $output);
         }
 
         $command = call_user_func($commandCallable, $url);

src/Composer/Repository/Vcs/GitDriver.php

@@ -53,7 +53,13 @@ class GitDriver extends VcsDriver
 
                 $command = sprintf('git clone --mirror %s %s', escapeshellarg($this->url), escapeshellarg($this->repoDir));
                 if (0 !== $this->process->execute($command, $output)) {
-                    throw new \RuntimeException('Failed to clone '.$this->url.', could not read packages from it ('.$this->process->getErrorOutput().')');
+                    $output = $this->process->getErrorOutput();
+            
+                    if (127 === $this->process->execute('git --version', $handler)) {
+                        throw new \RuntimeException('Failed to clone '.$this->url.', git isn\'t accessible through the console, please check your installation and your PATH env.' . "\n\n" . $this->process->getErrorOutput());
+                    }
+                    
+                    throw new \RuntimeException('Failed to clone '.$this->url.', could not read packages from it ('.$output.')');
                 }
             }
         }