[Exhentai] Display page links for failed downloads

[tkzv]

When you press Ctrl-C during a download, the program displays a message [exhentai][info] Use '...' as input URL to continue downloading from the current position. This is very convenient, since the URLs are impossible to guess, take time to find, and the crawler accesses them by number very slowly.

When a download and both fallback URLs fail (e.g. because of server troubles), the error message only displays the generated downloaded image name: [download][error] Failed to download ....jpg It would be more convenient, if it also displayed the page URLs.

[mikf]

With 2e1dab3 and 10c56a5, you'll be able to use

--print "error:https://exhentai.org/s/{image_token}/{gid}-{num}"

to display the image page URLs of failed downloads.

You can something similar with the current gallery-dl version by using a metadata post processor with "filename": "-" and "format": "https://exhentai.org/s/{image_token}/{gid}-{num}".