Fix pr builds

appveyor.yml

@@ -1,6 +1,5 @@
 version: 1.0.{build}
 build_cloud: electron-16
-skip_branch_with_pr: true
 image: electron-16-vs2017
 environment:
   DISABLE_CRASH_REPORTER_TESTS: true
@@ -9,6 +8,10 @@ environment:
   - TARGET_ARCH: x64
 build_script:
 - ps: >-
+    if(($env:APPVEYOR_PULL_REQUEST_HEAD_REPO_NAME -split "/")[0] -eq ($env:APPVEYOR_REPO_NAME -split "/")[0]) {
+      Write-warning "Skipping PR build for branch"; Exit-AppveyorBuild
+
+    } else {
       Add-Path "$env:ProgramFiles (x86)\Windows Kits\10\Debuggers\x64"
 
       $env:path = "$env:ProgramFiles (x86)\Windows Kits\10\Debuggers\x64;$env:path"
@@ -30,12 +33,13 @@ build_script:
         python script\bootstrap.py --target_arch=$env:TARGET_ARCH --dev
         python script\build.py -c D
       }
-
       if ($? -ne 'True') {
         throw "Build failed with exit code $?"
       } else {
         "Build succeeded."
       }
+    }
+
 test_script:
 - ps: >-
     if (Test-Path Env:\ELECTRON_RELEASE) {