It should not be necessary to make changes to Lustre's source tree just to start building Lustre against a different minor version of ZFS. Lustre on the master branch can be built successfully against a number of recent ZFS releases. It should not be necessary to make a Lustre source tree change to, for instance, start using ZFS 0.6.4.2 in Intel's build farm instead of ZFS 0.6.4.1. That is a build farm decision, not a source code implied limitation.

Build farm decisions should be separate from the Lustre source tree.