Try updating pip for appveyor.

Error did not disappear after having a pip install script. According to pypa/pip#3804 one just needs to update pip.
rqelibari · Mar 8, 2017 · 31488ea · 31488ea
1 parent 9aee90e
commit 31488ea
Showing 1 changed file with 1 addition and 0 deletions.
diff --git a/appveyor.yml b/appveyor.yml
@@ -12,6 +12,7 @@ init:
   - "echo Testing with %PYTHON%"
 
 install:
+  - "%PYTHON%\\python.exe -m pip install --upgrade pip"
   - "%PYTHON%\\python.exe -m pip install -r dev-requirements.txt"
 
 build: off