Fix race condition in room stats. (#6029)

Broke in #5971

Basically the bug is that if get_current_state_deltas returns no new updates and we then take the max pos, its possible that we miss an update that happens in between the two calls. (e.g. get_current_state_deltas looks up to stream pos 5, then an event persists and so getting the max stream pos returns 6, meaning that next time we check for things with a stream pos bigger than 6)

1 files changed, 1 insertions, 0 deletions

diff --git a/changelog.d/6029.bugfix b/changelog.d/6029.bugfix
new file mode 100644
index 0000000000..9ea095103b
--- /dev/null
+++ b/changelog.d/6029.bugfix
@@ -0,0 +1 @@
+Fix room and user stats tracking.