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##### SUMMARY
The "source" folder of my collection contains several files that are not directly related to the collection itself. E.g. a `.gitignore`, a `.github` folder, a `Makefile` etc.
When using `ansible-galaxy collection build <folder>`, these files are included in the generated tarball. This is especially hurtful when the source folder also contains a Python venv that I use for developing.

##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
ansible-galaxy

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible 2.9.0.dev0
  config file = /etc/ansible/ansible.cfg
  configured module search path = [u'/home/egolov/.ansible/plugins/modules', u'/usr/share/ansible/plugins/modules']
  ansible python module location = /home/egolov/Devel/ansible/ansible/lib/ansible
  executable location = /home/egolov/Devel/ansible/ansible/bin/ansible
  python version = 2.7.15 (default, Oct 15 2018, 15:26:09) [GCC 8.2.1 20180801 (Red Hat 8.2.1-2)]

```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below
empty
```

##### OS / ENVIRONMENT
Fedora


##### STEPS TO REPRODUCE
Build a collection :)

##### EXPECTED RESULTS
I'd expect only collection-relevant files/folders (those that are listed in the spec/docs) to be included.


##### ADDITIONAL INFORMATION
Alternatively, a ignore file as suggested by @bcoca  in https://github.com/ansible/ansible/pull/59121/files#r304554334 could be a fix for this.

''' create an options parser for bin/ansible '''
        super(GalaxyCLI, self).init_parser(
            desc="Perform various Role and Collection related operations.",
        )
        
        common = opt_help.argparse.ArgumentParser(add_help=False)
        common.add_argument('-s', '--server', dest='api_server', help='The Galaxy API server URL')
        common.add_argument('--api-key', dest='api_key',
                            help='The Ansible Galaxy API key which can be found at '
                                 'https://galaxy.ansible.com/me/preferences. You can also use ansible-galaxy login to '
                                 'retrieve this key or set the token for the GALAXY_SERVER_LIST entry.')
        common.add_argument('-c', '--ignore-certs', action='store_true', dest='ignore_certs',
                            default=C.GALAXY_IGNORE_CERTS, help='Ignore SSL certificate validation errors.')
        opt_help.add_verbosity_options(common)
        force = opt_help.argparse.ArgumentParser(add_help=False)
        force.add_argument('-f', '--force', dest='force', action='store_true', default=False,
                           help='Force overwriting an existing role or collection')
        github = opt_help.argparse.ArgumentParser(add_help=False)
        github.add_argument('github_user', help='GitHub username')
        github.add_argument('github_repo', help='GitHub repository')
        offline = opt_help.argparse.ArgumentParser(add_help=False)
        offline.add_argument('--offline', dest='offline', default=False, action='store_true',
                             help="Don't query the galaxy API when creating roles")
        default_roles_path = C.config.get_configuration_definition('DEFAULT_ROLES_PATH').get('default', '')
        roles_path = opt_help.argparse.ArgumentParser(add_help=False)