Cover lost when converting fb2 to mobi by command line

[J C]

When converting a fb2 to mobi with the GUI, everything is ok: even if you don't select "use cover from source file" (and of course, no other route for the cover is specified), it always takes the cover from the source fb2 file and inserts it in the final mobi file.
However, when using the command line, it doesn't work, and no cover is inserted in the final mobi unless you splicitly specify a route for a cover (an independent jpg file). Examples:

ebook-convert xxxx.fb2 xxxx.mobi --output-profile kindle ---> no cover in the final mobi
ebook-convert xxxx.fb2 xxxx.mobi --output-profile kindle --prefer-metadata-cover ---> no cover in the final mobi

NOTE: The following warning appears during the conversion process: "Unsupported coverpage nine-type 'image/jpg' (id=#cover.jpg)"

As I said before, it works perfectly with the same source fb2 file when using the GUI (the cover is inserted in the final mobi file, no matter if you select the option "use cover from source file" or not)

[Kovid Goyal (kovid)]

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 status incomplete

[J C (buzondejc)]

Attached book in fb2 format

[Kovid Goyal (kovid)]

Fixed in branch lp:calibre. The fix will be in the next release. calibre is usually released every Friday.

 status fixreleased