When shadowing a federated user, if the display name is changed, it
should get updated and returned in the user name attribute. This patch
fixes a bug where the display_name was getting updated, but not the old
display_name was being returned.
Closes-Bug: #1566494
Change-Id: I155d3a9e4c90a3d22d0b30e35276c9ddbb65ae6d
(cherry picked from commit 562b81dd4a)