Delete does not work

[Halbaroth]

The following code:

let () = 
   let l = Ancient.mark [0] in 
   Ancient.delete l 

produces the error

ocamlrun: ancient_c.c:386: ancient_delete: Assertion `!Is_in_heap_or_young (v)' failed 

The code is compiled with OCaml 4.14.2 with ocaml-option-nnp,ocaml-option-fp and both the master branch and the latest release of Ancient.

If I replace [0] with the empty [], I got a segment fault.

This bug is triggered in GeneWeb.