Assigning MR in sidebar does not update sidebar state

Summary

Assigning MR to someone in sidebar works, but sidebar state is not updated

Expected behavior

Sidebar should update itself after assigning team member.

/cc @alfredo1

Added frontend label

Reassigned to @alfredo1

It looks like assignee data is missing from PUT response.

/cc @rspeicher

/cc @jschatz1

Reassigned to @jschatz1

Reassigned to @iamphill

mentioned in commit 32be8bd2

mentioned in merge request !3877 (merged)

Status changed to closed by merge request !3877 (merged)

mentioned in commit a600b4b1

Milestone changed to 8.7

mentioned in issue #14939 (closed)

mentioned in commit 44a18c64

mentioned in issue #17176 (closed)