Merge pull request #175 from danepowell/issue-174

Fixes #174: Compatibility with older Git versions.

src/Patches.php

@@ -361,32 +361,13 @@ protected function getAndApplyPatch(RemoteFilesystem $downloader, $install_path,
       $downloader->copy($hostname, $patch_url, $filename, FALSE);
     }
 
-    // Modified from drush6:make.project.inc
-    $patched = FALSE;
     // The order here is intentional. p1 is most likely to apply with git apply.
     // p0 is next likely. p2 is extremely unlikely, but for some special cases,
     // it might be useful. p4 is useful for Magento 2 patches
     $patch_levels = array('-p1', '-p0', '-p2', '-p4');
-    foreach ($patch_levels as $patch_level) {
-      if ($this->io->isVerbose()) {
-        $comment = 'Testing ability to patch with git apply.';
-        $comment .= ' This command may produce errors that can be safely ignored.';
-        $this->io->write('<comment>' . $comment . '</comment>');
-      }
-      $checked = $this->executeCommand('git -C %s apply --check -v %s %s', $install_path, $patch_level, $filename);
-      $output = $this->executor->getErrorOutput();
-      if (substr($output, 0, 7) == 'Skipped') {
-        // Git will indicate success but silently skip patches in some scenarios.
-        //
-        // @see https://github.com/cweagans/composer-patches/pull/165
-        $checked = false;
-      }
-      if ($checked) {
-        // Apply the first successful style.
-        $patched = $this->executeCommand('git -C %s apply %s %s', $install_path, $patch_level, $filename);
-        break;
-      }
-    }
+
+    // Attempt to apply with git apply.
+    $patched = $this->applyPatchWithGit($install_path, $patch_levels, $filename);
 
     // In some rare cases, git will fail to apply a patch, fallback to using
     // the 'patch' command.
@@ -510,4 +491,45 @@ protected function arrayMergeRecursiveDistinct(array $array1, array $array2) {
     return $merged;
   }
 
+  /**
+   * Attempts to apply a patch with git apply.
+   *
+   * @param $install_path
+   * @param $patch_levels
+   * @param $filename
+   *
+   * @return bool
+   *   TRUE if patch was applied, FALSE otherwise.
+   */
+  protected function applyPatchWithGit($install_path, $patch_levels, $filename) {
+    // Do not use git apply unless the install path is itself a git repo
+    // @see https://stackoverflow.com/a/27283285
+    if (!is_dir($install_path . '/.git')) {
+      return FALSE;
+    }
+
+    $patched = FALSE;
+    foreach ($patch_levels as $patch_level) {
+      if ($this->io->isVerbose()) {
+        $comment = 'Testing ability to patch with git apply.';
+        $comment .= ' This command may produce errors that can be safely ignored.';
+        $this->io->write('<comment>' . $comment . '</comment>');
+      }
+      $checked = $this->executeCommand('git -C %s apply --check -v %s %s', $install_path, $patch_level, $filename);
+      $output = $this->executor->getErrorOutput();
+      if (substr($output, 0, 7) == 'Skipped') {
+        // Git will indicate success but silently skip patches in some scenarios.
+        //
+        // @see https://github.com/cweagans/composer-patches/pull/165
+        $checked = FALSE;
+      }
+      if ($checked) {
+        // Apply the first successful style.
+        $patched = $this->executeCommand('git -C %s apply %s %s', $install_path, $patch_level, $filename);
+        break;
+      }
+    }
+    return $patched;
+  }
+
 }