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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.

"""
        Exits with the specified return code unless the
        option --ignore-errors was specified
        """
        if not context.CLIARGS['ignore_errors']:
            raise AnsibleError('- you can use --ignore-errors to skip failed roles and finish processing the list.')
    @staticmethod
    def _display_role_info(role_info):
        text = [u"", u"Role: %s" % to_text(role_info['name'])]
        text.append(u"\tdescription: %s" % role_info.get('description', ''))
        for k in sorted(role_info.keys()):
            if k in GalaxyCLI.SKIP_INFO_KEYS:
                continue
            if isinstance(role_info[k], dict):
                text.append(u"\t%s:" % (k))
                for key in sorted(role_info[k].keys()):
                    if key in GalaxyCLI.SKIP_INFO_KEYS:
                        continue
                    text.append(u"\t\t%s: %s" % (key, role_info[k][key]))
            else:
                text.append(u"\t%s: %s" % (k, role_info[k]))
        return u'\n'.join(text)
    @staticmethod
    def _resolve_path(path):