Created attachment 1231274 [details]
backtrace

Description of problem:
Segfault during custom partition

Version-Release number of selected component (if applicable):
Fedora-Server-netinst-x86_64-25-1.3.iso

How reproducible:
always

Steps to Reproduce:
- Booted up from a USB stick, UEFI. sda is a fresh 1TB hard drive, sdb is a drive I'm ignoring, sdc is the boot media
- Select sda in disk selection, custom partition
- Hit the autopart button
- Shrink /home to 800 GiB, increase swap to an admittedly ludicrous 48GiB in case I ever try to hibernate, clear the size on /home and update again to grow to fit
- Go to the modify window for the volume group
- change the name, check the encrypt checkbox
- Crash happens upon hitting save

I've got a core dump if anyone really wants it, but since I don't feel like hosting it anywhere I'm going to attach the backtrace from gdb (also, I'm only doing the thread that crashed). The highlight of that is that bs_size_add is being called with size2=NULL, and if you go up a few frames that's because blivet's Size.__add__ is called with other=None. So maybe it's actually blivet's fault, or something higher up. I dunno.

Logs to follow.