Duh, got it: if next-1.3.1-lib is grafted, then the path to SQLite,
libfixposix, etc. _inside the compress binary_ will not be updated.
So if we garbage-collect after that, the binary will try to FFI-load
non-existing libraries.

Note that this is only a problem because Next depends on FFI libraries.
Compressing pure-SBCL binaries should not be a problem.

Thanks for your help!

-- 
Pierre Neidhardt
https://ambrevar.xyz/