I accidentally allowed a "dnf group remove mate-desktop", unaware that it would also remove a number of dependencies.
I tried to roll back the transaction with a "dnf history undo last" but it fails on an error where it thinks that the group name is a package:
# dnf history undo last
Last metadata expiration check: 2:00:42 ago on Fri 07 Dec 2018 12:17:28 AM EST.
Undoing transaction 11, from Fri 07 Dec 2018 02:12:45 AM EST
No package @mate-desktop available.
Error: no package matched
It is assumed that it is otherwise impossible to do dnf history transactions on groups.
fedora 30 still
This bug appears to have been reported against 'rawhide' during the Fedora 31 development cycle.
Changing version to '31'.