We'd need more details on the failure, but in general terms,
installer is having a lot of work done on it right now, it's not
surprising that it's busted, and individual bugs don't necessarily need
reporting at this time, as the code (particularly partitioning stuff) is
under constant revision. It might be best to wait till things calm down
a little before filing specific bugs.
I have a 1/2 TB disc with a couple partitions up front for windows.
Booting the last bootable live composition and trying to choose an
automatic partitioning scheme suggests there is no room.
If you have time to drop by
#anaconda you might be able to run your issue by the team there
informally though, and check if it's something they're aware of.
I'll certainly head over there this morning as soon as I can, thanks!