segfault when upgrading to using sprockets 4

[michaelglass]

Env: Ubuntu 16.04
Ruby: 2.5.3
sprockets: 4.0.0-beta8
sassc: 2.0.1
sassc-rails: 2.1.1
rails: 5.2.2.1

Howdy,

when we updated to Sprockets 4 beta, we started getting segfault flakes in different files (the same ~ 3-4 files so far, but sometimes they compile fine).

(see https://gist.github.com/michaelglass/4c2e635f1ba27ac91b19171fcd9216d1)

Any ideas? What information can I give to narrow this down?

[michaelglass]

fixed by disabling concurrency, see: rails/sprockets#581 (comment)