diff --git a/src/workflow/ArcanistLandWorkflow.php b/src/workflow/ArcanistLandWorkflow.php
--- a/src/workflow/ArcanistLandWorkflow.php
+++ b/src/workflow/ArcanistLandWorkflow.php
@@ -701,19 +701,21 @@
 
       // Collapse just the landing branch onto master.
       // Leave its children on the original branch.
-      $err = $repository_api->execPassthru(
-        'rebase --collapse --keep --logfile %s -r %s -d %s',
-        $this->messageFile,
-        $branch_range,
-        $this->onto);
+      if ($branch_root !== $branch_rev_id) {
+        $err = $repository_api->execPassthru(
+          'rebase --collapse --keep --logfile %s -r %s -d %s',
+          $this->messageFile,
+          $branch_range,
+          $this->onto);
 
-      if ($err) {
-        $repository_api->execManualLocal(
-          'rebase --abort');
-        $this->restoreBranch();
-        throw new ArcanistUsageException(
-          "Squashing the commits under {$this->branch} failed. ".
-          "Manually squash your commits and run 'arc land' again.");
+        if ($err) {
+          $repository_api->execManualLocal(
+            'rebase --abort');
+          $this->restoreBranch();
+          throw new ArcanistUsageException(
+            "Squashing the commits under {$this->branch} failed. ".
+            "Manually squash your commits and run 'arc land' again.");
+        }
       }
 
       if ($repository_api->isBookmark($this->branch)) {
@@ -734,7 +736,7 @@
       // check if the branch had children
       list($output) = $repository_api->execxLocal(
         "log -r %s --template %s",
-        hgsprintf("children(%s)", $this->branch),
+        hgsprintf("children(%s) - children(%s)", $this->branch, $this->onto),
         '{node}\n');
 
       $child_branch_roots = phutil_split_lines($output, false);
@@ -985,9 +987,11 @@
           $this->branch,
           $common_ancestor));
 
-      $repository_api->execxLocal(
-        '--config extensions.mq= strip -r %s',
-        $branch_root);
+      if ($branch_root !== '') {
+        $repository_api->execxLocal(
+          '--config extensions.mq= strip -r %s',
+          $branch_root);
+      }
 
       if ($repository_api->isBookmark($this->branch)) {
         $repository_api->execxLocal(