Picture of book without ISBN disappears after restart

When I add a book with a picture and without ISBN field filled, the book with its picture appears in the book list of my_library_1 after clicking on ADD button.
If I restart the software, book still appears but without the picture. But the picture file is still in the ~/.alexandria/my_library_1/.

This bug is annoying. My Alexandria version is 0.7.1

Note : there are also pictures of book I deleted from my_library_1 (moved to my_library_2) in the folder. There is also a lot of .cover.orig picture files. I think they appear when I change the picture of a book. There should be a way to clean up all these unneeded files.

Thanks for your help

String.hash result isn't the same across run, so cover cannot be retrieved from book.ident

Maybe using Digest::MD5 here?

alexandria-book-collection-manager/lib/alexandria/models/book.rb

Line 42 in 09326df

@isbn || @title.hash.to_s

Thanks, @g-maxime for figuring this out!