DON'T use the cryptonomex/graphene repository for the live BitShares network! This is the development repository, which differs from BitShares in some aspects.
The correct repository for the live network is
https://github.com/bitshares/bitshares-2 . If you click on that link, there will be a "releases" link above the list of files. Currently it says "16 releases". Click on that link, it will take you to a list of released versions.
(Currently, ) at the top of the release list there's a GUI release which you can ignore. Scroll down to the latest BitShares release. There was some confusion about the version number - it's called v2.0.151111 but it was actually released on 2015-11-01. To the left of the release version you can see the repository tag of the version, i. e. v2.0.151101. There is also the tag 2.15.306 which points to the exact same repository revision. This is the version you should use for your build.