Unpin pip again

Author: betatim

docs/source/changelog.rst

@@ -27,6 +27,9 @@ Bug fixes
   buildpack in :pr:`633` by :user:`betatim`.
 - Update to version 5.7.6 of the `notebook` package used in all environments
   in :pr:`628` by :user:`betatim`.
+- Switch to newer version of jupyter-server-proxy to fix websocket handling
+  in :pr:`646` by :user:`betatim`.
+- Update to pip v19.0.3 in :pr:`647` by :user:`betatim`.
 
 
 Version 0.8.0

repo2docker/buildpacks/python/__init__.py

@@ -63,7 +63,6 @@ def get_assemble_scripts(self):
         if os.path.exists(requirements_file):
             assemble_scripts.append((
                 '${NB_USER}',
-                'pip install "pip<19" && ' + \
                 '{} install --no-cache-dir -r "{}"'.format(pip, requirements_file)
             ))