deployer: Branch settings in hosts.yml are ignored

Hi,

I have the following setup with Deployer v6.5.0: hosts.yml:

typo3.example.com:
  hostname: example.com
  user: typo3
  stage: production
  roles: app
  branch: master
  deploy_path: "~/"
typo3-staging.example.com:
  hostname: example.com
  user: typo3-staging
  stage: staging
  roles: app
  branch: develop
  deploy_path: "~/"

deploy.php:

<?php
namespace Deployer;

require_once 'recipe/common.php';

/**
 * Setup
 */
inventory('hosts.yml');

set('allow_anonymous_stats', false);
set('typo3_webroot', 'public');
set('deploy_path_local', '/tmp');
set('release_name', date('Y-m-d_H-i-s'));

/*
 * Repository
 */
set('repository', 'git@some.com/location.git');

// [Optional] Allocate tty for git clone. Default value is false.
set('git_tty', true);

/*
 * Shared files / directories
 */
set('shared_files', [
    '{{typo3_webroot}}/typo3conf/LocalConfiguration.php',
    '{{typo3_webroot}}/.htaccess',
    '.env',
]);

set('shared_dirs', [
    '{{typo3_webroot}}/fileadmin',
    '{{typo3_webroot}}/typo3temp',
    '{{typo3_webroot}}/typo3conf/l10n',
    'var',
]);

/*
 * Cleanup
 */
set('clear_paths', [
    '.git/',
    'build/',
    '.editorconfig',
    '.env.example',
    '.gitignore',
    '.gitattributes',
    'composer.json',
    'composer.lock',
    'deploy.php',
    'hosts.yml',
    '*.md',
]);

/*
 * Helper
 */
set('copy_dirs', [
    '.',
]);

set('writable_dirs', [
    '{{typo3_webroot}}/fileadmin',
    '{{typo3_webroot}}/typo3temp',
    '{{typo3_webroot}}/typo3conf',
]);

/**
 * Custom Tasks
 */
/*
 * Local build
 */
task('deploy:build', function () {
    set('deploy_path', get('deploy_path_local'));
    invoke('deploy:prepare');
    invoke('deploy:release');
    invoke('deploy:update_code');
    invoke('deploy:vendors');
    invoke('deploy:clear_paths');
})->local();

/*
 * Upload local => external
 */
task('deploy:upload', function () {
    upload(
        '{{deploy_path_local}}/release/',
        '{{release_path}}',
        [
            'options' => [
                '--delete'
            ]
        ]
    );
});

/*
 * Updates
 */
task('deploy:cli_scripts', function () {
    run('{{release_path}}/vendor/bin/typo3cms install:fixfolderstructure');
    run('{{release_path}}/vendor/bin/typo3cms install:generatepackagestates');
    run('{{release_path}}/vendor/bin/typo3cms database:updateschema');
});

/**
 * Deployment
 */
task('deploy', [
    'deploy:info',
    'deploy:prepare',
    'deploy:lock',
    'deploy:release',
    'deploy:build',
    'deploy:copy_dirs',
    'deploy:upload',
    'deploy:shared',
    'deploy:writable',
    'deploy:cli_scripts',
    'deploy:symlink',
    'deploy:unlock',
    'cleanup',
])->desc('Deploy your project');

after('deploy', 'success');
after('deploy:failed', 'deploy:unlock');

What happens: If I deploy the staging stage with vendor/bin/dep deploy staging it deploys a version on the correct host, but always the master-Branch. It works only, if a explicitly add the --branch-option to the deploy-command.

Result on the command line:

user@host:~$ vendor/bin/dep deploy staging
✈︎ Deploying develop on example.com
➤ Executing task deploy:prepare
✔ Executing task deploy:lock
✔ Executing task deploy:release
➤ Executing task deploy:build
✔ Executing task deploy:prepare
✔ Executing task deploy:release
➤ Executing task deploy:update_code
Klone nach '/tmp/releases/2019-10-28_09-23-36' ...
remote: Enumerating objects: 4188, done.
remote: Counting objects: 100% (4188/4188), done.
remote: Compressing objects: 100% (2072/2072), done.
remote: Total 4188 (delta 1820), reused 4147 (delta 1786)
Empfange Objekte: 100% (4188/4188), 6.26 MiB | 0 bytes/s, Fertig.
Löse Unterschiede auf: 100% (1820/1820), Fertig.
✔rüfe Konnektivität ... Fertig.
✔ Executing task deploy:vendors
✔ Executing task deploy:clear_paths
✔ Ok
✔ Executing task deploy:copy_dirs
➤ Executing task deploy:upload
✔ Executing task deploy:shared
✔ Executing task deploy:writable
✔ Executing task deploy:cli_scripts
✔ Executing task deploy:symlink
✔ Executing task deploy:unlock
✔ Executing task cleanup
Successfully deployed!

What should happen: Deployer should respect the branch-setting in the hosts.yml.

What I know so far: This condition isn’t resolved to true in my case: https://github.com/deployphp/deployer/blob/861f1a34bb72c762422856b5281ac7a9975b20aa/recipe/deploy/update_code.php#L61-L64

How to resolve this issue? Do I missed something?