return vmr sync on prs

.vsts-ci.yml

@@ -10,6 +10,13 @@ trigger:
     - internal/release/6.*
     - internal/release/7.*
 
+resources:
+  repositories:
+    - repository: vmr
+      type: github
+      name: dotnet/dotnet
+      endpoint: dotnet
+
 parameters:
 - name: vmrBranch
   displayName: dotnet/dotnet branch to push to
@@ -372,6 +379,17 @@ stages:
       vmrBranch: ${{ variables.VmrBranch }}
       isBuiltFromVmr: false
 
+# In case the VMR Build stage is temporarily disabled, the VMR synchronization step is run to validate
+# that the PR can be merged and later synchronized into the VMR without problems.
+- ${{ if and(eq(variables['Build.Reason'], 'PullRequest'), parameters.disableVmrBuild) }}:
+  - stage: Synchronize_VMR
+    displayName: Synchronize VMR
+    dependsOn: []
+    jobs:
+    - template: eng/pipelines/templates/jobs/vmr-synchronization.yml
+      parameters:
+        vmrBranch: ${{ variables.VmrBranch }}
+
 - ${{ if and(ne(variables['System.TeamProject'], 'public'), notin(variables['Build.Reason'], 'PullRequest')) }}:
   - stage: Publish
     dependsOn:

eng/pipelines/vmr-sync.yml

@@ -1,9 +1,10 @@
+pr: none
+
 trigger:
   batch: true
   branches:
     include:
     - main
-    - master
     - release/*
 
 resources: