This code checks if the user has somehow posted a group deletion for a group that has "system" scope. If so, then the delete is not done and an input error is displayed. Note that in normal use the group manager page does not display a delete button for "system" groups, so normally this does not happen - only if the user manually messes with the $POST variables.
Related issues
Bug #5294: System users and groups not fully protected from deletion
Redmine #5294 Do not delete a system group
This code checks if the user has somehow posted a group deletion for a group that has "system" scope. If so, then the delete is not done and an input error is displayed.
Note that in normal use the group manager page does not display a delete button for "system" groups, so normally this does not happen - only if the user manually messes with the $POST variables.