Actually we don't need the $wgUnblockGroups config setting.

Change 167157 had a related patch set uploaded by leucosticte:
Add $wgBlockGroups config setting The $wgBlockGroups config setting makes it possible to restrict users to only blocking users who are not in certain groups. For example:

https://gerrit.wikimedia.org/r/167157

I have some doubt that "wheel wars where admins keep blocking and unblocking each other" really occurs often enough to be worth the added complexity of having this configuration option and having to decide what goes in it for each group. Let them play around until 'crats can desysop them both.

Keep in mind that in practice these lists are going to be more along the lines of "array( 'bot', 'reviewer', 'autoreview', 'accountcreator', 'import', 'transwiki', 'ipblock-exempt', 'oversight', 'founder', 'rollbacker', 'autoreviewer', 'researcher', 'filemover', 'checkuser', 'templateeditor', 'massmessage-sender', 'OTRS-member', 'abusefilter', 'epcoordinator', 'eponline', 'epcampus', 'epinstructor', 'oauthadmin', 'confirmed' )" than "array( 'bot' )" and would have to be updated every time a new group gets added.

If a wiki really wants this, it should be done in an extension. For one thing, it's not unheard of for a sysop to legitimately block another sysop, but this would unconditionally prevent that, if the configuration mentioned in the description were implemented. Also, we currently don't have anything even remotely related to hierarchies like this in the core, and I don't think it would be good to start.

(In reply to Brad Jorsch from comment #3)

Keep in mind that in practice these lists are going to be more along the
lines of "array( 'bot', 'reviewer', 'autoreview', 'accountcreator',
'import', 'transwiki', 'ipblock-exempt', 'oversight', 'founder',
'rollbacker', 'autoreviewer', 'researcher', 'filemover', 'checkuser',
'templateeditor', 'massmessage-sender', 'OTRS-member', 'abusefilter',
'epcoordinator', 'eponline', 'epcampus', 'epinstructor', 'oauthadmin',
'confirmed' )" than "array( 'bot' )" and would have to be updated every time
a new group gets added.

One could do, a la SpecialListgrouprights.php,

$allGroups = array_unique( array_merge(
array_keys( $groupPermissions ),
array_keys( $revokePermissions ),
array_keys( $addGroups ),
array_keys( $removeGroups ),
array_keys( $groupsAddToSelf ),
array_keys( $groupsRemoveFromSelf )
) );

And then array_diff the ones one doesn't want.

(In reply to Nathan Larson from comment #5)

One could do, a la SpecialListgrouprights.php,

$allGroups = array_unique( array_merge(
array_keys( $groupPermissions ),
array_keys( $revokePermissions ),
array_keys( $addGroups ),
array_keys( $removeGroups ),
array_keys( $groupsAddToSelf ),
array_keys( $groupsRemoveFromSelf )
) );

And then array_diff the ones one doesn't want.

Oh wait, maybe one couldn't do that.