e2e : Stale device lists

[ylecollen]

element-hq/element-web#2305

[richvdh]

reopening this because I think the algorithm we implemented was bogus

[richvdh]

we need port matrix-org/matrix-js-sdk#425 / matrix-org/matrix-js-sdk#431 here.

[ara4n]

@manuroe does the commit above mean this is done now?

[giomfo]

@ara4n no, port matrix-org/matrix-js-sdk#431 is not done yet.

[manuroe]

It has been done in matrix-org/matrix-ios-sdk#299.