Use a dynamic branch name in the README (#241)

features/scaffold-package-readme.feature

@@ -50,6 +50,10 @@ Feature: Scaffold a README.md file for an existing package
       """
       *This README.md is generated dynamically from the project's codebase
       """
+    And the {PACKAGE_PATH}/local/wp-cli/default-readme/README.md file should contain:
+      """
+      wp package install wp-cli/default-readme:dev-master
+      """
     When I run `wp package uninstall wp-cli/default-readme`
     Then STDOUT should contain:
       """

src/ScaffoldPackageCommand.php

@@ -259,6 +259,7 @@ public function package_readme( $args, $assoc_args ) {
 			'package_short_name'            => $bits[1],
 			'package_name_border'           => str_pad( '', strlen( $composer_obj['name'] ), '=' ),
 			'package_description'           => isset( $composer_obj['description'] ) ? $composer_obj['description'] : '',
+			'branch'                        => $branch,
 			'required_wp_cli_version'       => ! empty( $composer_obj['require']['wp-cli/wp-cli'] ) ? str_replace( [ '~', '^', '>=' ], 'v', $composer_obj['require']['wp-cli/wp-cli'] ) : 'v1.3.0',
 			'shields'                       => '',
 			'has_commands'                  => false,

templates/readme-installing.mustache

@@ -9,5 +9,5 @@ wp package install {{package_name}}:@stable
 To install the latest development version of this package, use the following command instead:
 
 ```bash
-wp package install {{package_name}}:dev-master
+wp package install {{package_name}}:dev-{{branch}}
 ```