Update comment and get rid of related drupal_is_cli() call.

islandora.module

@@ -2105,7 +2105,10 @@ function islandora_conditionally_clear_cache() {
   $functions = array(
     // Object changes in response to a form.
     'form_execute_handlers' => 'islandora_clear_cache_all',
-    // Object changes in response to a batch.
+    // Object changes in response to a batch. Note that this will not match on
+    // a drush batch, as drush uses a different set of functions to run
+    // batches. We intentionally do not clear batches in response to drush
+    // batches, since they are not in response to GUI actions.
     '_batch_process' => 'islandora_schedule_cache_clear_for_batch',
   );
 
@@ -2145,10 +2148,9 @@ function islandora_schedule_cache_clear_for_batch() {
 
   $scheduled = isset($scheduled) || isset($batch['islandora_cache_clear_scheduled']);
 
-  if ($scheduled || !isset($batch['id']) || drupal_is_cli()) {
+  if ($scheduled || !isset($batch['id'])) {
     // We do not wish to do anything if we are either already scheduled or the
-    // batch is not running. Also, if the batch is running on the CLI (via drush
-    // or otherwise).
+    // batch is not running.
     return;
   }