spec.workingDir(checkoutDir);
                    spec.commandLine("git", "checkout", effectiveRefSpec);
                });

                String checkoutHash = GitInfo.gitInfo(checkoutDir).getRevision();
                logger.lifecycle("Checkout hash for {} is {}", project.getPath(), checkoutHash);
                writeFile(new File(project.getBuildDir(), "refspec"), checkoutHash);
            });