Maffray's bipartisan even-pair conjecture

A graph is bipartisan if it is Berge, contains no $L(K_{3,3}\setminus e)$ and no double diamond, and neither $G$ nor $\overline{G}$ contains a long prism. An even pair is a pair of vertices such that every chordless path between them has even length. Maffray's conjecture. If $G$ is bipartisan with at least two vertices, then at least one of $G$ and $\overline{G}$ contains an even pair. This would generalize the bull-free Berge graph theorem and could shorten the proof of the strong perfect graph theorem. The survey presents it as an open conjecture.