When combining bracketed images, only the first operation is completed without errors. If one tries to combine another set of bracketed images after the first set is done, several assistants (wizards?) and processing windows are opened and the file can't be saved at the end or processing.

Reproducible: Always

Steps to Reproduce:
1. Select a set of bracketed images and then Click tools -> Combine bracketed images (I'm translating from portuguese, menu names may not be exactly these)
2. Click next, next, next, finish on the wizard window
3. Preview and save the combined image
4. Repeat steps 1 and 2 for another set of bracketed images
5. Several processing windows are opened. The more consecutive operations you try, the more processing windows are opened.
6. Close the spare windows and try to preview and save the combined image in the remaining one.
7. An error is displayed informing that the file could not be saved. Again, the more consecutive operations you try, the more error messages are displayed. Sometimes the file is saved despite the error message(s), sometimes it is not saved.


Actual Results:  
Multiple processing windows are opened after the wizard is finished and multiple error messages are displayed when trying to process and save the combined image. The file may or may not be saved.

Expected Results:  
Only one processing window should be displayed after the wizard is finished. No error should occur when trying to process the images and the combined image should be allways saved.

To process other sets of bracketed images, the user must close and restart Digikam after each set is processed. And Digikam takes a looooooong time to open.