preupgrade with limited disk space?

[Per Bothner]

This may be just a documentation issue, but now, with SSDs,
we're back to the old problem of limited disk space.
Of course preupgrade needs a lot of disk space for all the
packages it downloads. Is there a way to use an external
USB drive for temporary storage?  If not, temporarily
clear out some space in another partition, such as /home?

This page: https://fedoraproject.org/wiki/How_to_use_PreUpgrade
talks about not enough space in /boot - but it doesn't talk about
the problem of not enough space on root.
-- 
	--Per Bothner
per at bothner.com   http://per.bothner.com/