Fixing two user groups with the same ID

Question

Suddenly, my home directory is in the group messagebus instead of the usual staff.
(I blame texlive for this, but have no evidence.)

The problem is that both groups have the same ID:

$ dscl . -read /Groups/staff
AppleMetaNodeLocation: /Local/Default
GeneratedUID: ABCDEFAB-CDEF-ABCD-EFAB-CDEF00000014
GroupMembers: FFFFEEEE-DDDD-CCCC-BBBB-AAAA00000000
GroupMembership: root
Password: *
PrimaryGroupID: 20
RealName: Staff
RecordName: staff BUILTIN\Users
RecordType: dsRecTypeStandard:Groups
SMBSID: S-1-5-32-545

$ dscl . -read /Groups/messagebus
AppleMetaNodeLocation: /Local/Default
GeneratedUID: CF898A47-EA83-4E18-AE17-C05E56FBC550
Password: *
PrimaryGroupID: 20
RealName: messagebus
RecordName: messagebus
RecordType: dsRecTypeStandard:Groups

What is the safe way to get rid of the messagebus group (or give it a different ID)?
“Safe” here meaning of course that I don't damage my staffgroup.

Answer 1

Use the find command (and save the output listing. This may take a while)

find / -group messagebus -print

to ensure that ownership for files can be corrected later with a chgrp command.

The following be used

dscl . -change /Groups/messagebus PrimaryGroupID 20 10000