I have managed to make a local install build of the engine from sources, however, when I package empty test project, for main game binary (not the bootstrap) I get default UE4Game.exe which, contrary to official/launcher UE builds, will not boot the packaged game directly by default. It needs to be launched with ../../../MyCool.uproject argument (which is what bootstrap exe does)
Distributed/Launcher engine builds create self-sufficient executable binary when you package game project (i.e. bootstrap not required) usually named as MyProject-WinXX-GameConfiguration.exe
What can cause that? For the record, there is no such thing as rocket in last 20 or so version of UE4.x, in fact, even the keyword itself basically non-existent in recent code and only mentioned in comments.