##### SUMMARY
If you have executable files in your source code they are not kept in the tarball.

Could be related to https://github.com/ansible/ansible/blob/99d7f150873011e7515851db9b44ff486efa9d77/lib/ansible/galaxy/collection.py#L763

This was noticed as I had some auxiliary scripts in my repo.

Need to also consider scripts in `files/` if/when Collections support roles.

This seems to fail the "principal of least suprise"

**Proposal 1: Keep on stripping executable flags**

Add some line to the output
`WARNING: tests/coverage.sh: source file has executable flag, though this will be ignored in generated tar.gz`
Update developing a collection documentation page
Update integration tests to ensure that executable mode is always stripped.
Update code to link to this issue

**Proposal 2: Allow executible flags**

Update developing a collection documentation page
Update integration tests to ensure that executable mode is preserved
Update code to link to this issue
Changelog


##### ISSUE TYPE
- Bug Report

##### COMPONENT NAME
ansible-galaxy

##### ANSIBLE VERSION
```paste below
2.10
```

##### STEPS TO REPRODUCE
<!--- Describe exactly how to reproduce the problem, using a minimal test-case -->

<!--- Paste example playbooks or commands between quotes below -->
```yaml

```

<!--- HINT: You can paste gist.github.com links for larger files -->


monkeypatch.setattr(GalaxyCLI, 'execute_install', MagicMock())
    cli = GalaxyCLI(args=['ansible-galaxy', 'install'])
    cli.run()
    return cli
@pytest.mark.parametrize('requirements_file', [None], indirect=True)
def test_parse_requirements_file_that_doesnt_exist(requirements_cli, requirements_file):
    expected = "The requirements file '%s' does not exist." % to_native(requirements_file)
    with pytest.raises(AnsibleError, match=expected):
        requirements_cli._parse_requirements_file(requirements_file)
@pytest.mark.parametrize('requirements_file', ['not a valid yml file: hi: world'], indirect=True)
def test_parse_requirements_file_that_isnt_yaml(requirements_cli, requirements_file):
    expected = "Failed to parse the requirements yml at '%s' with the following error" % to_native(requirements_file)
    with pytest.raises(AnsibleError, match=expected):
        requirements_cli._parse_requirements_file(requirements_file)
@pytest.mark.parametrize('requirements_file', [('''
# Older role based requirements.yml
- galaxy.role
- anotherrole
''')], indirect=True)
def test_parse_requirements_in_older_format_illega(requirements_cli, requirements_file):
    expected = "Expecting requirements file to be a dict with the key 'collections' that contains a list of " \
               "collections to install"
    with pytest.raises(AnsibleError, match=expected):
        requirements_cli._parse_requirements_file(requirements_file, allow_old_format=False)
@pytest.mark.parametrize('requirements_file', ['''
collections:
- version: 1.0.0
'''], indirect=True)
def test_parse_requirements_without_mandatory_name_key(requirements_cli, requirements_file):