Large block edits present a fatal error

[aokod]

Block edits which require existing (non-air) blocks to be replaced (large copy/paste operations and the loading of grandiose schematics) lead to a fatal error:

[19:58:29] Player fssp is executing command "//schem load large_schematic" in world "Classic" at world age 463154109.
[19:58:30] Player fssp is executing command "//paste" in world "Classic" at world age 463154135.
Err  [19:58:30] Failure report: 
  :(   | Cuberite has encountered an error and needs to close
       | SIGSEGV: Segmentation fault
       |
       | Cuberite Jenkins x86_64-linux-gnu -DCMAKE_BUILD_TYPE=Release (master) (id: #174)
       | from commit 5fa45182e87bc3c1b7d28ab74d914c93f9b6fbef

The same crash has been produced on the latest version of Cuberite with other intensive block operations:

[20:10:13] Player fssp is executing command "//copy" in world "Classic" at world age 463163494.
[20:10:24] Player fssp is executing command "//paste" in world "Classic" at world age 463163706.
Err  [20:10:24] Failure report: 
  :(   | Cuberite has encountered an error and needs to close
       | SIGSEGV: Segmentation fault