User avatar fails to display properly when using #displayUser under some conditions

Condition:

• A user is logged in and thus has had his avatar displayed in the UI (ie #userDisplay has been called already)
• You're using #displayUser to display another user's avatar
• That other user has no avatar set and ($profileDoc.getObject('XWiki.XWikiGroups')) is false for this use (not sure what this means TBH)

Regression introduced in XWIKI-4022 at following line in commit https://github.com/xwiki/xwiki-platform/commit/0b31a22e63f52edd4eed3f5c4640fe4844e3e2ac#diff-bc2bc1864e4da7e06875c7e7b6665a11R232