Attempt to fix appveyor failing with AttributeError: '_NamespacePath' object has no attribute 'sort' on 3.5/3.6issue27

1 files changed, 6 insertions, 4 deletions

diff --git a/appveyor.yml b/appveyor.yml
index 51053ff..567e1a5 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -20,10 +20,12 @@ install:
 # We need to install the C extensions that BTrees setup-requires
 # separately because we've seen problems with the BTrees build cleanup step trying
 # to delete a .pyd that was still open.
-  - pip install persistent
-  - pip install BTrees
-  - pip install zope.testrunner
-  - pip install .[test]
+  - python -m pip install -U pip
+  - pip install -U setuptools
+  - pip install -U persistent
+  - pip install -U BTrees
+  - pip install -U zope.testrunner
+  - pip install -U .[test]
 
 build: false