I'm about to start the process of getting IMPALA-5174 committed to the toolchain. This patch changes gflags to allow 'hidden' flags that won't show up on /varz etc.
The toolchain glog has a dependency on gflags, meaning that the installed glog library needs to be built against the installed gflag library. So when the new gflag gets pulled in, you will need the new glog as well. However, the toolchain scripts won't detect that anything has changed for glog, because there's no version number change (changing the toolchain build ID doesn't cause the toolchain scripts to invalidate dependencies). Rather than introduce a spurious version bump with an empty patch file or something, I figured in this case it's easiest to ask developers to manually delete their local glog, and then bin/bootstrap_toolchain.py will download the most recent glog that's built against gflag. This is a one-time thing. I'll send out instructions about how to do this when the toolchain is updated.
