bug#49439: grafts cause “guix environment” to get killed with OOM

[Ricardo Wurmus]

With a recent version of Guix, “guix environment” will not 
terminate on its own, keeps the CPU busy, and gets killed when the 
system eventually runs out of memory.

$ guix describe -f channels

--8<---------------cut here---------------start------------->8---
(list (channel
       (name 'guix)
       (url "/home/rekado/dev/gx/branches/master")
       (commit
         "685cfdec94e5e48c4ad28de53466a28dfc258edb")))
--8<---------------cut here---------------end--------------->8---


$ guix environment pigx-scrnaseq
[wait until it gets killed]

The problem disappears when grafts are disabled:

$ guix environment --no-grafts pigx-scrnaseq
$ [env] yay!

--
Ricardo