frobby-0.9.0-r1.ebuild is EAPI 4
The revision you are referring to doesn't exist in Gentoo tree [1] as of commit bcc24a2640. [1]: https://packages.gentoo.org/packages/sci-mathematics/frobby
Sorry, I have been a little bit too fast. It is in tree now.
amd64 stable
x86 stable. Closing.