Backporting r5403 to release branch

program/include/rcube_session.php

@@ -393,6 +393,18 @@ class rcube_session
   }
 
 
+  /**
+   * Re-read session data from storage backend
+   */
+  public function reload()
+  {
+    if ($this->key && $this->memcache)
+      $this->mc_read($this->key);
+    else if ($this->key)
+      $this->db_read($this->key);
+  }
+
+
   /**
    * Serialize session data
    */

program/steps/mail/compose.inc

@@ -31,6 +31,14 @@ $MESSAGE = NULL;
 $COMPOSE_ID = get_input_value('_id', RCUBE_INPUT_GET);
 $_SESSION['compose'] = $_SESSION['compose_data_'.$COMPOSE_ID];
 
+// give replicated session storage some time to synchronize
+$retries = 0;
+while ($COMPOSE_ID && !is_array($_SESSION['compose']) && $RCMAIL->db->is_replicated() && $retries++ < 5) {
+  usleep(500000);
+  $RCMAIL->session->reload();
+  $_SESSION['compose'] = $_SESSION['compose_data_'.$COMPOSE_ID];
+}
+
 // Nothing below is called during message composition, only at "new/forward/reply/draft" initialization or
 // if a compose-ID is given (i.e. when the compose step is opened in a new window/tab).
 if (!is_array($_SESSION['compose']))