Description of problem:
Ran a kickstart install with F23 nightly 2015-07-17 boot.iso, in a VM with two CPUs (I think that may matter). Kickstart is http://jskladan.fedorapeople.org/kickstarts/root-user-crypted-net.ks . The crash doesn't happen on all attempts, only on some; I noticed it happen on a couple of openQA test attempts, restarting the test usually made it work.

Version-Release number of selected component:
anaconda-23.16-1

The following was filed automatically by anaconda:
anaconda 23.16-1 exception report
Traceback (most recent call first):
  File "/usr/lib64/python3.4/site-packages/pyanaconda/threads.py", line 126, in wait_all
    for name in names:
  File "/usr/lib64/python3.4/site-packages/pyanaconda/install.py", line 172, in doInstall
    threadMgr.wait_all()
  File "/usr/lib64/python3.4/threading.py", line 868, in run
    self._target(*self._args, **self._kwargs)
  File "/usr/lib64/python3.4/site-packages/pyanaconda/threads.py", line 247, in run
    threading.Thread.run(self, *args, **kwargs)
RuntimeError: dictionary changed size during iteration

Additional info:
addons:         com_redhat_kdump
cmdline:        /usr/bin/python3  /sbin/anaconda
cmdline_file:   BOOT_IMAGE=vmlinuz initrd=initrd.img inst.stage2=hd:LABEL=Fedora-23-x86_64 quiet inst.ks=http://jskladan.fedorapeople.org/kickstarts/root-user-crypted-net.ks
dnf.rpm.log:    Jul 22 17:57:41 INFO --- logging initialized ---
executable:     /sbin/anaconda
hashmarkername: anaconda
kernel:         4.2.0-0.rc2.git1.1.fc23.x86_64
product:        Fedora
release:        Cannot get release name.
type:           anaconda
version:        23