Revert change to setup.py with mistletoe, breaking install from sdist.

This reverts commit 500bcc2.

requirements-dev.txt

@@ -1,4 +1,3 @@
-mistletoe
 mock
 wheel
 torch_geometric

setup.py

@@ -16,10 +16,8 @@
 
 import os
 import platform
-import re
 import subprocess
 import sys
-import urllib.parse
 
 import setuptools
 from setuptools import find_namespace_packages
@@ -30,9 +28,6 @@
 # setuptools must be imported prior to distutils.
 from distutils import spawn
 from distutils.command import build
-import mistletoe.markdown_renderer
-import mistletoe.span_token
-import mistletoe.token
 # pylint:enable=g-bad-import-order
 
 
@@ -123,46 +118,14 @@ def get_version():
   """Get version from version module."""
   version_path = os.path.join(os.path.dirname(__file__), 'tensorflow_gnn')
   sys.path.insert(0, version_path)
-  # pytype: disable=import-error
-  # pylint: disable=g-import-not-at-top
+  # pytype: disable=import-error  # pylint: disable=g-import-not-at-top
   from version import __version__ as v
   return v
 
 
-# Get the long description from the README.md file and convert
-# relative links on github.com to absolute and versioned links for pypi.org.
-def _convert_readme_markdown(md, branch):
-  """Converts README.md into long description for pypi.org."""
-
-  version = get_version()
-  if branch == 'main' and not re.match(r'.*dev\d*$', version):
-    raise ValueError(
-        'Must edit setup.py to set _convert_readme_markdown(..., branch=...) '
-        f'to the github branch for version "{version}", other than "main".')
-
-  def update_relative_link(link):
-    url = urllib.parse.urlparse(link.target)
-    if url.scheme or url.netloc or url.path.startswith('/'):
-      return  # Leave absolute paths and URLs unchanged.
-    link.target = (
-        f'https://github.com/tensorflow/gnn/blob/{branch}/{link.target}')
-
-  def update_token(token):
-    if isinstance(token, mistletoe.span_token.Link):
-      update_relative_link(token)
-    for child in getattr(token, 'children', []):
-      update_token(child)
-
-  with mistletoe.markdown_renderer.MarkdownRenderer() as renderer:
-    document = mistletoe.Document(md)
-    update_token(document)
-    return renderer.render(document)
-
+# Get the long description from the README file.
 with open('README.md') as fp:
-  _LONG_DESCRIPTION = _convert_readme_markdown(
-      fp.read(),
-      branch='main',  # <<< MUST EDIT TO RELEASE BRANCH.
-  )
+  _LONG_DESCRIPTION = fp.read()
 
 
 console_scripts = [