My mistake was giving into the temptation to land the build system branch because I didn’t want it to rot. Problem is that it had a bunch of follow-up issues that really needed to be done before the tag, not the least of which was working with @Techatrix from ZLS team to make sure ZLS can continue to function correctly in 0.17. Those are the main release blockers at the moment.
On the other hand, the good news is that while the tag is delayed, progress on other features has not. For example, 0.17 will greatly increase the robustness and practical usability of incremental compilation, in particular with respect to debug information and linker capability. Similarly, the way that ZLS and build system communicate now opens the doors to some nice future enhancements.
With all that in mind, the fact that I didn’t successfully pull off a short release cycle means that there is still the need to do a short release cycle to catch up with LLVM.