Use pre-installed yarn version on appveyor

geowarin · geowarin · commit 78890c69e40a · 2017-02-15T10:52:53.000+01:00
diff --git a/appveyor.yml b/appveyor.yml
@@ -7,8 +7,6 @@ environment:
 
 install:
   - ps: Install-Product node $env:nodejs_version
-  - choco install yarn
-  - refreshenv
   - yarn install
 
 test_script:
