[0.15.14] Crash when using poison cap on large group

[Gishe]

We recently crashed multiple times when using a poison capsule on a large group of biters. It did not seem to matter if we had the poison down before they ran through or if we dropped it right on top of them. Attached are two logs of the crashes from the connected client.

[orzelek]

Should be fixed already in 0.15.15.