Installation up to the proposal screen. Then select Partitioning and change
s.th. After return to the proposal start the installation. The formatting
screen appears baut after some time an error popup says:

Storage modification failed
System error code was: -3005
Formatting /dev/... with none

The partition with the failure is swap, that appaerently shall be
formatted with type none.

Don't have time to investigate further but it seems that the error only
occurs if and only if the partitioning is changed from the proposal. If
the initial proposal is accepted as is, no error occurs.

Tested this on two different machines, x86 and x86_64: Same behaviour.

And no, I don't have the time to provide y2log now. Some responsible
person will have to investigate this.