Merge immediately if branch is up to date and passes tests

.github/mergify.yml

@@ -82,15 +82,36 @@ pull_request_rules:
       review:
         type: APPROVE
 
-  - name: Add ready-to-merge labeled PRs to merge queue
+  - name: Add outdated, ready-to-merge PRs to merge queue
     conditions:
       # All branch protection rules are implicit: https://docs.mergify.com/conditions/#about-branch-protection
       - base!=stable
       - label=ready-for-merge
       - label!=do-not-merge
+      - "#commits-behind > 0"
     actions:
       queue:
 
+  - name: Merge up to date, ready-to-merge PRs
+    conditions:
+      # All branch protection rules are implicit: https://docs.mergify.com/conditions/#about-branch-protection
+      - base!=stable
+      - label=ready-for-merge
+      - label!=do-not-merge
+      - check-success=test-suite-success
+      - "#approved-reviews-by >= 1"
+      - "#commits-behind == 0"
+    actions:
+      merge:
+        method: squash
+        commit_message_template: |
+          {{ title }} (#{{ number }})
+
+            {{ body | get_section("## Issue Addressed", "") }}
+
+
+            {{ body | get_section("## Proposed Changes", "") }}
+
 queue_rules:
   - name: default
     batch_size: 8