bob: How to create an updated bootstrap tarball

Hi!

I am back again with another bob question. Sorry I have so many of these 
:)

On macOS or Linux, where you need a bootstrap.tar.gz file, you probably 
want to create a new version of the bootstrap right before you start the 
build. Is there a good way to do this with bob?

I don't want to do it "natively" because that would impact the pkgsrc tree 
I am currently using.

Should I just use "bob dev" to create a sandbox, run bootstrap in there 
and package the result? If so, would it make sense to have something like 
a "bob createbootstrap" command?

-- 
Benny