diff --git a/core/includes/form.inc b/core/includes/form.inc
index 67088c853f..8514462f71 100644
--- a/core/includes/form.inc
+++ b/core/includes/form.inc
@@ -755,58 +755,68 @@ function batch_set($batch_definition) {
       $batch['sets'][] = $batch_set;
     }
     else {
-      // The set is being added while the batch is running. Insert the new set
-      // right after the current one to ensure execution order, and store its
-      // operations in a queue. If multiple sets are being added while the batch
-      // is running ensure that each new one will be appended instead of
-      // prepended.
-      $append_after_index = $batch['current_set'];
-      $reached_current_set = FALSE;
-      foreach ($batch['sets'] as $index => $set) {
-        // As the indexes are not ordered numerically we need to first reach
-        // the index of the current set and then search for the proper place to
-        // append the new batch set.
-        if (!$reached_current_set) {
-          if ($index == $batch['current_set']) {
-            $reached_current_set = TRUE;
-          }
-          continue;
-        }
-        if ($index > $append_after_index) {
-          if (isset($set['appended_after_index'])) {
-            $append_after_index = $index;
-          }
-          else {
-            break;
-          }
-        }
+      // The set is being added while the batch is running.
+      _batch_append_set($batch, $batch_set);
+    }
+  }
+}
+
+/**
+ * Appends a batch set to a running batch.
+ *
+ * Inserts the new set right after the current one to ensure execution order,
+ * and store its operations in a queue. If multiple sets are being added while
+ * the batch is running ensure that each new one will be appended instead of
+ * prepended.
+ *
+ * @param &$batch
+ *   The batch array.
+ * @param $batch_set
+ *   The batch set.
+ */
+function _batch_append_set(&$batch, $batch_set) {
+  $append_after_index = $batch['current_set'];
+  $reached_current_set = FALSE;
+  foreach ($batch['sets'] as $index => $set) {
+    // As the indexes are not ordered numerically we need to first reach the
+    // index of the current set and then search for the proper place to append
+    // the new batch set.
+    if (!$reached_current_set) {
+      if ($index == $batch['current_set']) {
+        $reached_current_set = TRUE;
       }
-      $batch_set['appended_after_index'] = $append_after_index;
-
-      // Iterate by reference over the existing batch sets and assign them by
-      // reference in the new batch sets array in order not to break a retrieved
-      // reference to the current set. Among other places a reference to the
-      // current set is being retrieved in _batch_process(). We have to preserve
-      // the original indexes as they are used to generate the queue name of
-      // each batch set, as if we do not preserve the indexes of the existing
-      // batch sets the operations of the new batch will be queued in the queue
-      // of a previous batch set, because without index preservation we will be
-      // using not a new, but an existing and already used index for the new
-      // batch set.
-      // @see _batch_populate_queue().
-      $new_sets = [];
-      foreach ($batch['sets'] as $index => &$set) {
-        $new_sets[$index] = &$set;
-        if ($index == $append_after_index) {
-          $new_set_index = count($batch['sets']);
-          $new_sets[$new_set_index] = $batch_set;
-        }
+      continue;
+    }
+    if ($index > $append_after_index) {
+      if (isset($set['appended_after_index'])) {
+        $append_after_index = $index;
       }
-
-      $batch['sets'] = $new_sets;
-      _batch_populate_queue($batch, $new_set_index);
+      else {
+        break;
+      }
+    }
+  }
+  $batch_set['appended_after_index'] = $append_after_index;
+
+  // Iterate by reference over the existing batch sets and assign them by
+  // reference in the new batch sets array in order not to break a retrieved
+  // reference to the current set. Among other places a reference to the current
+  // set is being retrieved in _batch_process(). Additionally, we have to
+  // preserve the original indexes, as they are used to generate the queue name
+  // of each batch set, otherwise the operations of the new batch set will be
+  // queued in the queue of a previous batch set.
+  // @see _batch_populate_queue().
+  $new_sets = [];
+  foreach ($batch['sets'] as $index => &$set) {
+    $new_sets[$index] = &$set;
+    if ($index == $append_after_index) {
+      $new_set_index = count($batch['sets']);
+      $new_sets[$new_set_index] = $batch_set;
     }
   }
+
+  $batch['sets'] = $new_sets;
+  _batch_populate_queue($batch, $new_set_index);
 }
 
 /**
diff --git a/core/modules/system/tests/modules/batch_test/batch_test.callbacks.inc b/core/modules/system/tests/modules/batch_test/batch_test.callbacks.inc
index fea4ff6d5e..35c18fec75 100644
--- a/core/modules/system/tests/modules/batch_test/batch_test.callbacks.inc
+++ b/core/modules/system/tests/modules/batch_test/batch_test.callbacks.inc
@@ -15,7 +15,7 @@
  * Performs a simple batch operation.
  */
 function _batch_test_callback_1($id, $sleep, &$context) {
-  // No-op, but ensure the batch take a couple iterations.
+  // No-op, but ensure the batch takes a couple iterations.
   // Batch needs time to run for the test, so sleep a bit.
   usleep($sleep);
   // Track execution, and store some result for post-processing in the
@@ -39,7 +39,7 @@ function _batch_test_callback_2($start, $total, $sleep, &$context) {
   // Process by groups of 5 (arbitrary value).
   $limit = 5;
   for ($i = 0; $i < $limit && $context['sandbox']['count'] < $total; $i++) {
-    // No-op, but ensure the batch take a couple iterations.
+    // No-op, but ensure the batch takes a couple iterations.
     // Batch needs time to run for the test, so sleep a bit.
     usleep($sleep);
     // Track execution, and store some result for post-processing in the
@@ -63,7 +63,7 @@ function _batch_test_callback_2($start, $total, $sleep, &$context) {
  * Implements callback_batch_operation().
  */
 function _batch_test_callback_5($id, $sleep, &$context) {
-  // No-op, but ensure the batch take a couple iterations.
+  // No-op, but ensure the batch takes a couple iterations.
   // Batch needs time to run for the test, so sleep a bit.
   usleep($sleep);
   // Track execution, and store some result for post-processing in the
@@ -80,7 +80,7 @@ function _batch_test_callback_5($id, $sleep, &$context) {
  * Performs a simple batch operation.
  */
 function _batch_test_callback_6($id, $sleep, &$context) {
-  // No-op, but ensure the batch take a couple iterations.
+  // No-op, but ensure the batch takes a couple iterations.
   // Batch needs time to run for the test, so sleep a bit.
   usleep($sleep);
   // Track execution, and store some result for post-processing in the
@@ -95,7 +95,7 @@ function _batch_test_callback_6($id, $sleep, &$context) {
  * Performs a simple batch operation.
  */
 function _batch_test_callback_7($id, $sleep, &$context) {
-  // No-op, but ensure the batch take a couple iterations.
+  // No-op, but ensure the batch takes a couple iterations.
   // Batch needs time to run for the test, so sleep a bit.
   usleep($sleep);
   // Track execution, and store some result for post-processing in the
diff --git a/core/modules/system/tests/modules/batch_test/batch_test.module b/core/modules/system/tests/modules/batch_test/batch_test.module
index e169f61af9..76ae17b1da 100644
--- a/core/modules/system/tests/modules/batch_test/batch_test.module
+++ b/core/modules/system/tests/modules/batch_test/batch_test.module
@@ -183,7 +183,7 @@ function _batch_test_batch_6() {
 }
 
 /**
- * Batch 6: Performs two batches within a batch.
+ * Batch 7: Performs two batches within a batch.
  *
  * Operations:
  * - op 7 from 1 to 5,
@@ -197,11 +197,11 @@ function _batch_test_batch_7() {
   $sleep = (1000000 / $total) * 2;
 
   $operations = [];
-  for ($i = 1; $i <= round($total / 2); $i++) {
+  for ($i = 1; $i <= $total / 2; $i++) {
     $operations[] = ['_batch_test_callback_7', [$i, $sleep]];
   }
   $operations[] = ['_batch_test_nested_batch_callback', [[5, 6]]];
-  for ($i = round($total / 2) + 1; $i <= $total; $i++) {
+  for ($i = ($total / 2) + 1; $i <= $total; $i++) {
     $operations[] = ['_batch_test_callback_7', [$i, $sleep]];
   }
   $batch = [
@@ -254,7 +254,6 @@ function batch_test_stack($data = NULL, $reset = FALSE) {
   if (!isset($data)) {
     return $state->get('batch_test.stack');
   }
-  $state->resetCache();
   $stack = $state->get('batch_test.stack');
   $stack[] = $data;
   $state->set('batch_test.stack', $stack);