When installing on a system without enough disk space in /opt, the 'setup'
program will pop-up an error message indicating there is insufficient disk
space.  This problem can often be corrected without exiting from 'setup'. 
'setup' does not recalculate free disk space after you clear the pop-up window,
and installation is effectively blocked.  You must exit the 'setup' program and
restart it to continue (after freeing up disk space).

My expectation is that 'setup' would recalculate free disk space, before it
checks disk space again, if the pop-up is cleared, and NEXT is clicked to continue.

As is, you get the exact same error (no change in amounts shown as
required/free), if the pop-up is cleared, and NEXT is clicked to continue, even
if disk space has been made available.