A quick note, the repository for building the Linux kernel onboard the NVIDIA Jetson TX2 development kit has been updated. The repository is on the JetsonHacks account on Github, buildJetsonTX2Kernel.
I want to thank Shreeyak (https://github.com/Shreeyak) for pointing out a version identification issue, as well as building an alternative to pull the kernel sources from the NVIDIA Git repositories directly. While I ultimately chose not to use this approach in the JetsonHacks scripts, there is a pull request available which implements this. If you are developing on the Jetson professionally, you and your team should seriously consider this approach.