On append/merge not dispay bookmarks of PDF previous created

[hildogjr]

If I create two or more PDF files with this library and merge those file using the

pdf_merger.append(pdf_file, bookmark, import_bookmarks=True)

The resultant file have the root bookmarks as the previous files (which is fine) but it do not show the bookmarks present at the two initial files as low level bookmarks at the final PDF.

Appear that the append/merge method do not recognize the bookmarks created by tho own library even passing the command import_bookmarks=True.