Description of problem:
I had complete manual partitioning like this (everything else was default settings for Server netinst):

/ - 4,5 GiB
/boot - 512 MiB
swap - 512 MiB

this settings was set and used without a problem. Then I got to the spoke again and changed space for '/' to 4,55 GiB I clicked on Done without 'Update Settings' button and got this crash.

Version-Release number of selected component:
anaconda-23.19-1

The following was filed automatically by anaconda:
anaconda 23.19-1 exception report
Traceback (most recent call first):
  File "/tmp/updates/blivet/blivet.py", line 1716, in copy
    for mnt in removed:
  File "/tmp/updates/blivet/devicefactory.py", line 876, in _save_devicetree
    _blivet_copy = self.storage.copy()
  File "/tmp/updates/blivet/devicefactory.py", line 815, in configure
    self._save_devicetree()
  File "/tmp/updates/blivet/blivet.py", line 1678, in factoryDevice
    factory.configure()
  File "/tmp/updates/pyanaconda/ui/gui/spokes/custom.py", line 630, in _replace_device
    new_device = self._storage_playground.factoryDevice(dev_type, size, **kwargs)
  File "/tmp/updates/pyanaconda/ui/gui/spokes/custom.py", line 711, in _try_replace_device
    self._replace_device(selector=selector, **new_device_info)
  File "/tmp/updates/pyanaconda/ui/gui/spokes/custom.py", line 1179, in _save_right_side
    new_device_info, old_device_info)
  File "/tmp/updates/pyanaconda/ui/gui/spokes/custom.py", line 1631, in on_back_clicked
    self._save_right_side(self._current_selector)
UnboundLocalError: local variable 'removed' referenced before assignment

Additional info:
addons:         com_redhat_kdump
cmdline:        /usr/bin/python3  /sbin/anaconda
cmdline_file:   initrd=/test/jk/rawhide/initrd.img inst.repo=ftp://cobra02/rawhide/x86_64/os nokill resolution=1024x768 updates=http://cobra02/ks/jk/master_updates.img BOOT_IMAGE=/test/jk/rawhide/vmlinuz 
dnf.rpm.log:    Aug 17 10:39:14 INFO --- logging initialized ---
executable:     /sbin/anaconda
hashmarkername: anaconda
kernel:         4.2.0-0.rc6.git1.1.fc24.x86_64
product:        Fedora
release:        Cannot get release name.
type:           anaconda
version:        Rawhide