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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.

display.warning(u"- %s was NOT installed successfully: %s " % (role.name, to_text(e)))
                self.exit_without_ignore()
                continue
            
            if not no_deps and installed:
                if not role.metadata:
                    display.warning("Meta file %s is empty. Skipping dependencies." % role.path)
                else:
                    role_dependencies = role.metadata.get('dependencies') or []
                    for dep in role_dependencies:
                        display.debug('Installing dep %s' % dep)
                        dep_req = RoleRequirement()
                        dep_info = dep_req.role_yaml_parse(dep)
                        dep_role = GalaxyRole(self.galaxy, self.api, **dep_info)
                        if '.' not in dep_role.name and '.' not in dep_role.src and dep_role.scm is None:
                            
                            
                            continue
                        if dep_role.install_info is None:
                            if dep_role not in roles_left:
                                display.display('- adding dependency: %s' % to_text(dep_role))
                                roles_left.append(dep_role)
                            else:
                                display.display('- dependency %s already pending installation.' % dep_role.name)
                        else:
                            if dep_role.install_info['version'] != dep_role.version:
                                if force_deps:
                                    display.display('- changing dependant role %s from %s to %s' %
                                                    (dep_role.name, dep_role.install_info['version'], dep_role.version or "unspecified"))
                                    dep_role.remove()