Description of problem:
Trying to set existing partition size to a value larger than the original

Version-Release number of selected component:
anaconda-core-29.23-2.fc29.x86_64

The following was filed automatically by anaconda:
anaconda 29.23 exception report
Traceback (most recent call first):
  File "/usr/lib/python3.7/site-packages/blivet/deviceaction.py", line 458, in __init__
    raise ValueError("new size same as old size")
  File "/usr/lib/python3.7/site-packages/blivet/threads.py", line 53, in run_with_lock
    return m(*args, **kwargs)
  File "/usr/lib/python3.7/site-packages/blivet/blivet.py", line 874, in resize_device
    actions.append(ActionResizeDevice(device, new_size))
  File "/usr/lib/python3.7/site-packages/blivet/threads.py", line 53, in run_with_lock
    return m(*args, **kwargs)
  File "/usr/lib64/python3.7/site-packages/pyanaconda/ui/gui/spokes/custom_storage.py", line 834, in _handle_size_change
    self._storage_playground.resize_device(use_dev, use_size)
  File "/usr/lib64/python3.7/site-packages/pyanaconda/ui/gui/spokes/custom_storage.py", line 137, in decorated
    return func(*args, **kwargs)
  File "/usr/lib64/python3.7/site-packages/pyanaconda/ui/gui/spokes/custom_storage.py", line 1243, in _save_right_side
    self._handle_size_change(size, old_size, device)
  File "/usr/lib64/python3.7/site-packages/pyanaconda/ui/gui/spokes/custom_storage.py", line 2350, in _save_current_page
    self._save_right_side(selector)
  File "/usr/lib64/python3.7/site-packages/pyanaconda/ui/gui/spokes/custom_storage.py", line 2360, in on_selector_clicked
    self._save_current_page(old_selector)
  File "/usr/lib64/python3.7/site-packages/pyanaconda/ui/gui/spokes/lib/accordion.py", line 372, in process_event
    cb(old_selector, selector)
ValueError: new size same as old size

Additional info:
blivet-gui-utils.log: 
cmdline:        /usr/bin/python3  /sbin/anaconda --liveinst --method=livecd:///dev/mapper/live-base
cmdline_file:   BOOT_IMAGE=/images/pxeboot/vmlinuz root=live:CDLABEL=Fedora-WS-Live-Rawhide-20180808- rd.live.image quiet
executable:     /sbin/anaconda
hashmarkername: anaconda
kernel:         4.18.0-0.rc8.git1.1.fc29.x86_64
other involved packages: anaconda-gui-29.23-2.fc29.x86_64, python3-blivet-3.1.0-0.5.b2.fc29.noarch
product:        Fedora
release:        Fedora release 29 (Rawhide)
release_type:   pre-release
type:           anaconda
version:        rawhide