Reset state after applying stash, fixes #1254

src/Composer/Downloader/GitDownloader.php

@@ -157,6 +157,7 @@ class GitDownloader extends VcsDownloader
             if (0 !== $this->process->execute('git stash pop', $output, $path)) {
                 throw new \RuntimeException("Failed to apply stashed changes:\n\n".$this->process->getErrorOutput());
             }
+            $this->hasStashedChanges = false;
         }
     }