Bug 338724

My local collections include: 
- a path to separate partition with few hundred GB pictures and 
- a path to my desktop folder, where I ocassionaly put some pictures.

Recently I added a symlink on my desktop to quickly get to the folder with data which is a parent directory of my collection of pictures. When I ran digikam few days after:
- it took a few minutes to show any pictures,
- switching to other albums freezed the UI for few seconds,
- after switching albums it wasn't showing any thumbnails,
- htop showed two digikam processes eating 100% CPU.
- I killed it and ran it in console and the output showed output showed multiple lines being logged (about 3 times a second):
checkRetrySQLiteLockError: Detected locked database file. There is an active transaction. Waited but giving up now.

I killed digikam, I removed the symlink and everything went back to normal.

Reproducible: Always

Steps to Reproduce:
1. add two folders including images to collection,
2. add symlink from one to parent of another.


Actual Results:  
A big freeze.

Expected Results:  
Normal operation: either not following the symilnks or treating them as links to albums.