Flaky test `TestDepthChange`

[vladopajic]

Unit test TestDepthChange seams to be flaky. CI job has failed although change from PR couldn't affect it (since it had no change on source code), also other subsequent jobs have completed successfully.

Logs output from CI:

     puller_test.go:412: error getting interval for bin 4: storage: not found
--- FAIL: TestDepthChange (3.34s)
    --- PASS: TestDepthChange/move_peer_around (2.06s)
    --- FAIL: TestDepthChange/peer_moves_out_of_depth_then_back_in (1.28s)