GetAllUniqueRoleAssignments caching data key

[bezua]

Dear community,

It looks to me that there is a defect in GetAllUniqueRoleAssignments extension, preceisly EnsureGroupCache.
The cache key is groupLoginName which is unique for one site, but ambigious when working with many sites at once.

In SharePoint sites we can have sharepoint groups. Different sites can have same group name, but each contains different set of memebers.

The problem appears when crawling multpile sites with GetAllUniqueRoleAssignments. Since cache behind is a static dictionary, it remembers all processed site data from the beginning.
During crawling, when running GetAllUniqueRoleAssignments for a site where sharepoint groups are duplicated, you get old data from dictionary.