Change I74682c7b3732144138c87ca9037772b005df17d7 introduce an
alternative API to add and remove NSGroup members, however it also
removed the request retry instruction, which is wrong because the
request might still fail with HTTP 412 ("Precondition failed") error.
Closes-Bug: #1531819
Change-Id: Ifb05d3e812de5ff089d5bce2da429e30dcad4c25