it exits without errors:
2016-02-24 16:08:01 init message: Verifying wallet...
2016-02-24 16:08:01 CDBEnv::Open: LogDir=XXX ErrorFile=XXX
(end of the log)
no db.log nor wallet.dat is created
EDIT: on the same machine, there are three other wallets running fine.
Is this other machine running 15.10 as well?
Yes.
I spooled up an Ubuntu 15.10 instance today to test this myself. Nothing fancy going on, even using the distro-provided BDB. Daemon compiles fine (using the --with-incompatible-bdb) config flag and has been running all day.
I tried rebuilding from scratch, running the daemon with gen=0, no way.
It crashes without any hint. Not even segfault.