fix sending of messages to selection of users by status, fixes #1496

Closes #1496

Merge request studip/studip!935

app/controllers/course/members.php

@@ -564,7 +564,6 @@ class Course_MembersController extends AuthenticatedController
             $this->redirect(URLHelper::getURL('dispatch.php/messages/write', [
                 'default_subject' => $this->getSubject(),
                 'tmpsavesnd' => 1,
-                'course_id' => $this->course_id,
                 'emailrequest' => 1
             ]));
         } else {

app/controllers/messages.php

@@ -370,7 +370,7 @@ class MessagesController extends AuthenticatedController {
                     $query = "SELECT user_id, 'rec' AS snd_rec
                                       FROM seminar_user
                                       JOIN auth_user_md5 USING (user_id)
-                                      WHERE Seminar_id = ? AND seminar_user.visible != 'no'
+                                      WHERE Seminar_id = :course_id AND seminar_user.visible != 'no'
                                       ORDER BY Nachname, Vorname";
                 }
                 if ($query) {