'Install basic Read the Docs requirements into the Conda env.'

def install_core_requirements(self):

    requirements = ['mock', 'pillow']
    pip_requirements = ['recommonmark']
    if (self.project.documentation_type == 'mkdocs'):
        pip_requirements.append('mkdocs')
    else:
        pip_requirements.append('readthedocs-sphinx-ext')
        requirements.extend(['sphinx', 'sphinx_rtd_theme'])
    cmd = ['conda', 'install', '--yes', '--name', self.version.slug]
    cmd.extend(requirements)
    self.build_env.run(*cmd)
    pip_cmd = ['python', self.venv_bin(filename='pip'), 'install', '-U', '--cache-dir', self.project.pip_cache_path]
    pip_cmd.extend(pip_requirements)
    self.build_env.run(bin_path=self.venv_bin(), *pip_cmd)
