Currently the stdout and stderr from the Maven process is also used for the Sling Server Process. That is a problem because even after one Mojo is done, the server is still running and may still emit messages. Those overlap with the messages of the following Maven mojos. Therefore the stdout and stderr of the Sling server should be redirected to a special file.
The only drawback is, that in case of a central CI server, those additional files are not that easy to evaluate (need to be downloaded separately). Still this is much better than having overlapping log files of two independent processes (Maven and Sling Server).