I rolled Guix back to the commit that produced this VM and built a fresh VM. Unfortunately it did not reproduce this bug.
I doubt this was caused by the recent Guix infrastructure problems. I favor the memory leak theory proposed by Christopher Baines ... http://lists.gnu.org/archive/html/bug-guix/2018-11/msg00032.html ... for bug#33248: python-minimal compilation is breaking [1]. [1] http://lists.gnu.org/archive/html/bug-guix/2018-11/msg00032.html
