Fatal error is displayed when a page is shared with other users

[Niranjan]

Version master (16.10)

Browser : FF

Steps to reproduce:

1) Navigate to portfolio>pages
2) Click on one of the existing pages
3) Click on edit this page
4) Click on Share page
5) Select users from "share with" drop down
6) Search for the user and select it
7) Click on save

Expected result : The page should be shared with the user
Actual result: Fatal error message is displayed ( see attached)

Note: For 16.04 it works fine

[Kristina Hoeppner (kris-hoeppner)]

I couldn't replicate it and Niranjan couldn't either after clearning his DB that had been used for patch testing.