Prevent deleting executing operations

app/src/main/java/eu/faircode/email/DaoOperation.java

@@ -150,6 +150,8 @@ public interface DaoOperation {
     @Query("DELETE FROM operation WHERE id = :id")
     int deleteOperation(long id);
 
-    @Query("DELETE FROM operation WHERE folder = :folder")
-    int deleteOperations(long folder);
+    @Query("DELETE FROM operation" +
+            " WHERE folder = :folder" +
+            " AND state <> 'executing'")
+    int deletePendingOperations(long folder);
 }

app/src/main/java/eu/faircode/email/ServiceSend.java

@@ -414,7 +414,7 @@ public class ServiceSend extends ServiceBase {
             db.folder().setFolderError(outbox.id, null);
 
             // Delete pending operations
-            db.operation().deleteOperations(outbox.id);
+            db.operation().deletePendingOperations(outbox.id);
 
             // Requeue operations
             NotificationManager nm = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);