fix: Revert "feat(automerge): merge passing branch even if PR exists (#3097)"

This reverts commit 514d527d.

lib/workers/branch/automerge.js

@@ -8,23 +8,13 @@ async function tryBranchAutomerge(config) {
     return 'no automerge';
   }
   const existingPr = await platform.getBranchPr(config.branchName);
-
+  if (existingPr) {
+    return 'automerge aborted - PR exists';
+  }
   const branchStatus = await platform.getBranchStatus(
     config.branchName,
     config.requiredStatusChecks
   );
-
-  if (existingPr) {
-    if (branchStatus === 'success') {
-      if (existingPr.canRebase) {
-        await platform.mergeBranch(config.branchName, config.automergeType);
-        logger.info({ branch: config.branchName }, 'Branch automerged');
-        return 'automerged'; // Branch no longer exists
-      }
-      return 'automerge aborted - Human commits detected';
-    }
-    return 'automerge aborted - PR exists';
-  }
   if (branchStatus === 'success') {
     logger.debug(`Automerging branch`);
     try {

test/workers/branch/automerge.spec.js

@@ -31,20 +31,12 @@ describe('workers/branch/automerge', () => {
       expect(await tryBranchAutomerge(config)).toBe('branch status error');
     });
     it('returns false if PR exists', async () => {
-      platform.getBranchPr.mockReturnValueOnce({});
-      config.automerge = true;
-      config.automergeType = 'branch';
-      expect(await tryBranchAutomerge(config)).toBe(
-        'automerge aborted - PR exists'
-      );
-    });
-    it('returns false if PR exists and success branch', async () => {
       platform.getBranchPr.mockReturnValueOnce({});
       config.automerge = true;
       config.automergeType = 'branch';
       platform.getBranchStatus.mockReturnValueOnce('success');
       expect(await tryBranchAutomerge(config)).toBe(
-        'automerge aborted - Human commits detected'
+        'automerge aborted - PR exists'
       );
     });
     it('returns false if automerge fails', async () => {
@@ -62,12 +54,5 @@ describe('workers/branch/automerge', () => {
       platform.getBranchStatus.mockReturnValueOnce('success');
       expect(await tryBranchAutomerge(config)).toBe('automerged');
     });
-    it('merge branch if PR exists and have one commit and success branch', async () => {
-      platform.getBranchPr.mockReturnValueOnce({ canRebase: true });
-      config.automerge = true;
-      config.automergeType = 'branch';
-      platform.getBranchStatus.mockReturnValueOnce('success');
-      expect(await tryBranchAutomerge(config)).toBe('automerged');
-    });
   });
 });