[5.x] Fix target .git repo handling when exporting starter kit with…

… `--clear` (#11509)

src/StarterKits/Exporter.php

@@ -153,7 +153,9 @@ protected function clearExportPath()
             return $this;
         }
 
-        $this->files->cleanDirectory($this->exportPath);
+        $this->preserveGitRepository(function () {
+            $this->files->cleanDirectory($this->exportPath);
+        });
 
         return $this;
     }
@@ -257,4 +259,20 @@ protected function exportPackage(): self
 
         return $this;
     }
+
+    /**
+     * Prevent filesystem callback from affecting .git repository.
+     */
+    protected function preserveGitRepository($callback): void
+    {
+        $this->files->makeDirectory(storage_path('statamic/tmp'), 0777, true, true);
+
+        $this->files->moveDirectory($this->exportPath.'/.git', storage_path('statamic/tmp/.git'));
+
+        $callback();
+
+        $this->files->moveDirectory(storage_path('statamic/tmp/.git'), $this->exportPath.'/.git');
+
+        $this->files->deleteDirectory(storage_path('statamic/tmp'));
+    }
 }

tests/StarterKits/ExportTest.php

@@ -173,7 +173,11 @@ public function it_can_clear_target_export_path_with_clear_option()
             base_path('two'),
         ]);
 
-        // Imagine this exists from previous export
+        // Imagine we already have a target a git repo
+        $this->files->makeDirectory($this->targetPath('.git'), 0777, true, true);
+        $this->files->put($this->targetPath('.git/config'), 'Config.');
+
+        // And imagine this exists from previous export
         $this->files->makeDirectory($this->exportPath('one'), 0777, true, true);
         $this->files->put($this->exportPath('one/file.md'), 'One.');
 
@@ -195,10 +199,13 @@ public function it_can_clear_target_export_path_with_clear_option()
 
         $this->exportCoolRunnings(['--clear' => true]);
 
-        // But 'one' folder should exist after exporting with `--clear` option
+        // Our 'one' folder shouldn't exist after exporting with `--clear` option
         $this->assertFileDoesNotExist($this->exportPath('one'));
         $this->assertFileExists($this->exportPath('two'));
 
+        // But it should not clear `.git` directory
+        $this->assertFileExists($this->targetPath('.git/config'));
+
         $this->exportCoolRunnings();
 
         $this->cleanPaths($paths);