Description of problem:

The dropdown list of RAID levels to select from is empty in all instances that I tried.

Version-Release number of selected component (if applicable):

anaconda-21.14-1

How reproducible:

Always in rawhide, not in current fedora or rhel7.

Steps to Reproduce:
1) Choose Installation Destination
2) Select both disks (I have two)...Done
3) Choose "I want to review/modify..."
4) Choose "Click here to create..."
5) For Device Type select LVM
6) Press "Modify" next to Volume Group choices.
7) Observe that the RAID Level label is not hidden, but the dropdown menu next to it is empty.

It does the same with Device Type BTRFS.

Actual results:

Drop down list of RAID levels empty.

Expected results:

Should see a list of RAID levels that are supported for this fs.

Additional info:

So, if one selects Device Type RAID a dropdown list of RAID levels appears on
the Manual Partitioning spoke and it appears to be correct.

The drop down labels are distinctly named ComboBoxes, raidStoreFiltered and containerRaidStoreFiltered but both boxes are backed by the same raidLevelStore.

It's obvious that the problem lies in this line:

for (i, row) in enumerate(self._raidLevelCombo.get_model()):

which is an empty generator for the bad case, but I can't tell why this should be the case in one instance and not another.

It also seems weird to me that that the refilter method is called. Apparently this method works by sending a row-changed signal for each row in the raidStore, but there doesn't seem to be any method registered for handling this signal