When enabling epub support using the epub USE-flag it does not apply to okular (kde-apps/okular-16.08.2) as the USE-flag "ebook" is used instead. According to Okular documentation ebook-tools is the library used to parse epub files, and usage of ebook-tools for other purposes is not mentioned. I suggest that the epub USE-flag shall be used also in okular ebuild to enable epub-support. This is what at least I expect by such a USE-flag, especially since epub is a valid USE-flag for kde-frameworks/kfilemetadata. Reference: https://okular.kde.org/formats.php
Fine with me, anyone else want to chime in?
Imho ebook sounds more natural.
It's a little bit misleading - ebooks can come in many formats and contrary to the name ebook-tools really only ships libepub.
Let's change this to be consistent with frameworks?
Fixed in git commit 60996c376c373d5774a0fd21d3e1d420a77ac1a5.