Warning of ungraceful termination during packaging

[KristofMorva]

Hey,

at the end of packaging, we always get this warning:

UATHelper: Packaging (Windows (64-bit)):   LogSourceControl: Warning: ExitBackgroundCommandLineShell: cm shell didn't stop gracefully in 1.000000s.
PackagingResults: Warning: ExitBackgroundCommandLineShell: cm shell didn't stop gracefully in 1.000000s.

It happens right before ********** COOK COMMAND COMPLETED ********** when systems are torn down.

It happens with 1.6, but it also happened with a few other versions before this. UE is on 4.27.2.