sage sometimes leaves matlab processes that eat 100% cpu time

[sagetrac-cwitty]

I've found a way to somewhat reproducibly leave a matlab process eating 100% cpu time.

I log on to sage.math, start Sage, and run the following commands:

sage: m = matlab(matrix(RR, [[1]]))
sage: m.det()

Then I kill my local ssh client with "kill -9" (to make a non-clean ssh shutdown).

Often (not always, but I think more than half the time) this leaves a matlab process eating 100% of the cpu time.

Component: interfaces: optional

Issue created by migration from https://trac.sagemath.org/ticket/3504