Don't Build Twice on Branches with Pull Requests

appveyor.yml

@@ -37,6 +37,8 @@ cache:
 pull_requests:
   do_not_increment_build_number: true
 
+skip_branch_with_pr: true
+
 on_failure:
   - ps: Get-ChildItem .\_artifacts\*.zip | % { Push-AppveyorArtifact $_.FullName -FileName $_.Name }
   - ps: Get-ChildItem .\_artifacts\*.exe | % { Push-AppveyorArtifact $_.FullName -FileName $_.Name }