Users + Groups = Roles, duplicate name issue

I loaded a 7.4.x dump into a new 8.1.1 database and found out what happens
if you had the same name as both a user and a group. You can get users with
more rights than they had before.  I guess it is too late, but perhaps a
mention in the release text would have been a good idea. Advise people to
rename any group which has the same name as a user.

For example, if at 7.4.x I have:
  Group:    Is granted all rights to table:
    test      test_data
    acct      money_data

  Username:   Member of group:   And therefore gets all rights to table:
    ljb         test               test_data
    test        acct               money_data

After loading the dump into 8.1.1, the test user and test group get merged
into a single role, so the test user gets granted all rights to the test_data
table. In addition, 'ljb' now effectively is a member of the 'acct' group
(via the test role), so is granted all rights to the money_data table.