As the title suggests, cv-0.4.1.ebuild writes > SRC_URI="https://github.com/Xfennec/${PN}/archive/v${PV}.tar.gz" which downloads `v0.4.1.tar.gz'. Such filenames are confusing (without package names), and may collide with other source archives (many source tarballs from GitHub are named similarly). Therefore, it should be better to use > SRC_URI="https://github.com/Xfennec/${PN}/archive/v${PV}.tar.gz -> ${P}.tar.gz" (Finally, please forgive me if I am always stretching my nose too far...)
It also fails to build against sys-libs/ncurses[tinfo].
It also didn't install README.md and failed to respect CC and LDFLAGS.