When a new volume is created and/or when a brick is added to an existing volume, it should make sure that the GlusterFS version is the same in all the bricks. If this is not the case, it should throw a warning to the user.
Planing to keep 3.4.x branch as "internal enhancements" release without any features. So moving these bugs to 3.4.0 target milestone.
With the availability of op-version[1] feature, where all the storage nodes run 'compatible' versions of glusterfs binaries. It is not 'wrong' to have different bricks of a volume having different versions of glusterfs, as long as they are compatible. Closing this as not a bug. [1] - http://www.gluster.org/community/documentation/index.php/Features/Opversion