On April 30, 2022, ns-3.36 was published. This page lists some issues that have been fixed in the mainline since that time. The maintainers may make an update to this release to cover some or all of these issues.
Adding files to scratch/ triggers a rebuild
Prior to ns-3.36, one could build ns-3 libraries, add a program to scratch/, and call `./waf build` and only that program would be built and linked. With ns-3.36, the same operation triggers a recompilation of the whole project.
This bug was fixed in changeset 98eaf7a7
Users can either update their code with that specific patch, or upgrade to ns-3-dev version.