Why does the Lubuntu minimum install say that it requires 10.7 GB of available drive space?

I have a 4GB Dell Mini 9. I used UnetBootin following the instructions at pendrivelinux.com.

I have tried Xubuntu minimal install, Lubuntu minimal install, and vanilla Lubuntu, and all result in the same issue:

The second screen of the install 'Preparing to install Ubuntu' says 'for best results, please ensure that this computer has at least 10.7 GB available drive space'.

Am I doing something wrong? The system requirements for these OSes are much lower than 10.7GB.

The minimal size is only recommendation -- if you want you can change it.

In LiveCD environment (before running installation) open terminal and run

gksudo leafpad /usr/lib/ubiquity/plugins/ubi-prepare.py

at line 303, there's variable size and at line 310 you'll find this

min_disk_size = size * 2

just change the number 2 for adjustment (now the minimal size is 5 GB * 2, I've replaced it with 0.8), save the file and run Installator again.