Hello Sönke,
That was indeed it. Thank you! using --build-mode=singleFile with the newest version of dub unambiguously identified running out of memory as the issue (it died on web.d, in case you were interested). I tried with the beta dmd, but alas, it did not help (dying on d.d). I only have 1Gb of RAM on this server, so I am not surprised.
I suppose my best option would either be to provision more RAM on the server, or compile it in a VM on my OS X instance and just copy the binary.
Thanks for your help!
- Jan