The documentation for Child and Sibling mode clearly indicates that the baseline is only delivered to the target stream if the build is successful.
When looking at the console output, though, it appears that the delivery happens first and then the build steps. It looks like if the build fails, the delivery is then reverted.
This flow brings up several questions that I'm not able to find answers to. I'm sure that there are good reasons for why it happens this way, so please update the documentation to reflect this additional detail.