Actually add patch.

Markdown-3.0.1-pyaml.patch

@@ -0,0 +1,49 @@
+From 0b8d39920a0415f4b5149a4ee6d9b05455683cf7 Mon Sep 17 00:00:00 2001
+From: Waylan Limberg <waylan.limberg@icloud.com>
+Date: Thu, 14 Mar 2019 09:17:31 -0400
+Subject: [PATCH] Update CLI to support PyYAML 5.1
+
+This should avoid any warnings. We use `unsafe_load` because users may
+need to pass in actual Python objects. As this is only available from
+the CLI, the user has much worse problems if an attacker can use this
+as an attach vector.
+---
+ markdown/__main__.py | 14 +++++++++++---
+ 1 file changed, 11 insertions(+), 3 deletions(-)
+
+diff --git a/markdown/__main__.py b/markdown/__main__.py
+index 38d08fe..43e486c 100644
+--- a/markdown/__main__.py
++++ b/markdown/__main__.py
+@@ -26,9 +26,17 @@ import codecs
+ import warnings
+ import markdown
+ try:
+-    import yaml
++    # We use `unsafe_load` because users may need to pass in actual Python
++    # objects. As this is only available from the CLI, the user has much
++    # worse problems if an attacker can use this as an attach vector.
++    from yaml import unsafe_load as yaml_load
+ except ImportError:  # pragma: no cover
+-    import json as yaml
++    try:
++        # Fall back to PyYAML <5.1
++        from yaml import load as yaml_load
++    except ImportError:
++        # Fall back to JSON
++        from json import load as yaml_load
+ 
+ import logging
+ from logging import DEBUG, WARNING, CRITICAL
+@@ -97,7 +105,7 @@ def parse_options(args=None, values=None):
+             options.configfile, mode="r", encoding=options.encoding
+         ) as fp:
+             try:
+-                extension_configs = yaml.load(fp)
++                extension_configs = yaml_load(fp)
+             except Exception as e:
+                 message = "Failed parsing extension config file: %s" % \
+                           options.configfile
+-- 
+2.20.1
+