On Tue, 03 Jul 2018 23:42:28 +0200
ludo@gnu.org (Ludovic Courtès) wrote:

[..]
> Did you have troubles with substitutes?  In particular, did it hang as
> described in <https://bugs.gnu.org/31925>?  (I’m still experiencing it
> occasionally and I can’t believe I’m the only one.)

No. But it looks like you found your example to reproduce.

Björn