The issue has been on GitHub for a long time. However, it is known that at least technically, draws are possible on OGS (by moderator decision): Thoughts Regarding Komi Tie-Breaker
That linked game was a ranked game too, so Glicko2 as implemented here seems to be able to handle draws in one way or another.
It would still be really nice to get some word from @anoek on this…