Bitbucket is not "importing" users avatars from JIRA users as would be expected. It shows the empty gravatar.
This is a bit annoying.
But it gets even more annoying - if the admin tries to upload a new avatar image, it displays there for a split of second and then disappears and ... nothing.
I discovered that the user can change his gravatar.
There are 3 ways to solve this:
1- would resolve everything > import avatars when using JIRA managed user profiles
2 - If !1 > allow admin to change users' avatars
3 - if !1 and !2 > include a message to display to admin stating that he has no permission to change user avatar and that user should do it instead.