Download wheel files for manylinux for all the given packages.

def download_manylinux_wheels(self, abi, packages, directory):
        # type: (str, List[str], str) -> None
        """Download wheel files for manylinux for all the given packages."""
        # If any one of these dependencies fails pip will bail out. Since we
        # are only interested in all the ones we can download, we need to feed
        # each package to pip individually. The return code of pip doesn't
        # matter here since we will inspect the working directory to see which
        # wheels were downloaded. We are only interested in wheel files
        # compatible with lambda, which means manylinux1_x86_64 platform and
        # cpython implementation. The compatible abi depends on the python
        # version and is checked later.
        for package in packages:
            arguments = ['--only-binary=:all:', '--no-deps', '--platform',
                         'manylinux1_x86_64', '--implementation', 'cp',
                         '--abi', abi, '--dest', directory, package]
            self._execute('download', arguments)