`port rev-upgrade` exits with code 139

[René J.V. Bertin]

On Monday November 09 2015 11:39:27 Rainer Müller wrote:

> Exit code 139 is usually how a shell tells you the command died with
> signal 11, which is SIGSEGV (Segmentation Fault). The process made an
> invalid memory access and is terminated abruptly.

Except that I'm not getting the other messages that usually come with a crash. An earlier version of my mod to Pextlib did cause a SIGSEGV, and that was impossible to miss.
Is it possible that something in rev-upgrade spawns a background process with completely hidden output, of which the exit code is returned?

I guess I'll have to figure out how to get actual core dumps on that linux rig (Kubuntu 14.04). I seem to recall I already set the relevant ulimit.

R.