close 1101858 1:21.0.0-1 thanks Hello Thomas.
[ Please always CC me on bugs which I report. I read your message because I'm subscribed to debian-bugs-rc, but I can't always read it ]. Good news: I can build the current version in unstable just fine. I actually tried 20 times on machines with 1 CPU and 20 times on machines with 2 CPUs. Zero failures. So, I'm going to assume that this is fixed in the current version. If you tried to build it once and failed, maybe it's just random. Feel free to reopen with a lower severity, but in this case I will not be able to help with VMs to reproduce, as I can't reproduce it here. Thanks a lot.
