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I copied Dedian-9 template to Standalone-VM, and installed BBR in it following instructions from BBR README.md for Unix server version(without GUI). The message also occurred first time i started a daemon, after it downloaded data4.mdb.pak.
I have that OS on two machines, same thing
I think it could be related with "-march" option in clang/gcc compiler. If it still makes sense, you can try explicitly configure it with passing ARCH variable, try to pass "-D ARCH=native".
Let me know if it worked or not if you find time to try.
Mistery solved, neither time i gave it enough head room to unpak downloaded pak

So, that message is displayed when it runs out of disk space when bootstraping with mdb.pak mechanism, at least in a virtual machine