--fixtures and --markers are broken when there's a required option added in pytest_addoption()

Similar to https://github.com/pytest-dev/pytest/issues/1999

When you add a required option in pytest_addoption the --fixtures and --markers arguments cannot be used without specifying the required options. This was fixed for --help in https://github.com/pytest-dev/pytest/pull/2458.

Example

conftest.py

import pytest


def pytest_addoption(parser):
    parser.addoption("--please-work", action="store_true", required=True)


@pytest.fixture
def spam():
    return "spam"

Output

fixtures_required> pytest
usage: pytest [options] [file_or_dir] [file_or_dir] [...]
pytest: error: argument --please-work is required

>pytest --help 
usage: pytest [options] [file_or_dir] [file_or_dir] [...]

positional arguments:
  file_or_dir

general:
  -k EXPRESSION         only run tests which match the given substring
                        expression. An expression is a python evaluatable
                        expression where all names are substring-matched
                        against test names and their parent classes. Example:
                        -k 'test_method or test_other' matches all test
                        functions and classes whose name contains
                        'test_method' or 'test_other', while -k 'not
                        test_method' matches those that don't contain
                        'test_method' in their names. Additionally keywords
                        are matched to classes and functions containing extra
                        names in their 'extra_keyword_matches' set, as well as
                        functions which have names assigned directly to them.

<snip>

to see available markers type: pytest --markers
to see available fixtures type: pytest --fixtures
(shown according to specified file_or_dir or current dir if not specified)

fixtures_required>pytest --fixtures 
usage: pytest [options] [file_or_dir] [file_or_dir] [...]
pytest: error: argument --please-work is required

fixtures_required>pytest --markers 
usage: pytest [options] [file_or_dir] [file_or_dir] [...]
pytest: error: argument --please-work is required

Versions

Windows 10.0.16299.125 x64

Package    Version               Location
---------- --------------------- -------------------------
appdirs    1.4.3
attrs      17.3.0
colorama   0.3.9
funcsigs   1.0.2
packaging  16.8
pip        9.0.1
pluggy     0.6.0
py         1.5.2
pyparsing  2.2.0
pytest     3.3.2.dev45+g370daf04
setuptools 38.2.4
six        1.11.0
tox        2.9.1
virtualenv 15.1.0
wheel      0.30.0

Reproduce the example with a conftest.py defining a required pytest_addoption option, then compare the behavior of --fixtures and --markers with --help. Trace the pytest command-line handling for these options and add regression coverage showing they work without requiring unrelated options; done means both commands list their requested information successfully.