[Rock-dev] Release candidate of rock.core

[Sylvain Joyeux]

The rock-rc branch of https://github.com/rock-core/buildconf now
builds what should become the next rock.core release (as in: builds
fine in a 16.04 system from scratch, and tests that were passing still
pass). As usual, it needs testing.

To bootstrap from scratch:

   ruby autoproj_bootstrap git https://github.com/rock-core/buildconf
branch=rock-rc

To apply on an existing install, assuming that you have an up-to-date
base/scripts (from today):

   rock-release versions refs/heads/rock-rc >
autoproj/overrides.d/99-rock-rc.yml

After adding the version file, the safest thing to do is to check
what's different with

   autoproj status

(Note: the refs/heads/ is necessary because there was a rock-rc tag in
the buildconf repository. I just deleted the tag, but deletion of tags
is not propagated ... A.k.a. don't create tags for things that are
meant to be temporary)

Sylvain