[Pharo-dev] How to force a BaselineOf to load ?

Hi, I have a Pharo 4 (#40627) image that already contains P3. Now I want to update P3, without completely rebuilding this image from scratch. It seems as if an expression like Metacello new baseline: 'P3'; repository: 'github://svenvc/P3'; load. executed like $ ../bin/pharo build-trackit.image eval --save "Metacello new baseline: 'P3'; repository: 'github://svenvc/P3'; load" does not really reload the code. How can I force it to (re)load ? Thx, Sven