[ros-diffs] [dreimer] 46874: Introduce %_BUILDBOT_SVNSKIPMAINTRUNK% as first of maybe more coming BuildBot Vars to skip the updating of the main trunk source when ssvn is used to do so. If its being set to "1" it only updates rosapps and rostests if existant. This is needed for Olaf Siejka's Windows Buildbot project. As Default its set to "0" and thus all behaves as before. UNTESTED