Add --git-dir and --work-tree to user tests

Author: jablko

src/testRunner/externalCompileRunner.ts

@@ -55,11 +55,11 @@ abstract class ExternalCompileRunnerBase extends RunnerBase {
                     ts.Debug.assert(!!config.cloneUrl, "Bad format from test.json: cloneUrl field must be present.");
                     const submoduleDir = path.join(cwd, directoryName);
                     if (!fs.existsSync(submoduleDir)) {
-                        exec("git", ["clone", config.cloneUrl, directoryName], { cwd });
+                        exec("git", ["--work-tree", submoduleDir, "clone", config.cloneUrl, path.join(submoduleDir, ".git")], { cwd });
                     }
-                    exec("git", ["reset", "HEAD", "--hard"], { cwd: submoduleDir });
-                    exec("git", ["clean", "-f"], { cwd: submoduleDir });
-                    exec("git", ["pull", "-f"], { cwd: submoduleDir });
+                    exec("git", ["--git-dir", path.join(submoduleDir, ".git"), "--work-tree", submoduleDir, "reset", "HEAD", "--hard"], { cwd: submoduleDir });
+                    exec("git", ["--git-dir", path.join(submoduleDir, ".git"), "--work-tree", submoduleDir, "clean", "-f"], { cwd: submoduleDir });
+                    exec("git", ["--git-dir", path.join(submoduleDir, ".git"), "--work-tree", submoduleDir, "pull", "-f"], { cwd: submoduleDir });
 
                     types = config.types;