Icarus vvp asserts of_JOIN_DETACH on fork..join_none inside an automatic task

Icarus Verilog 12 (Debian vvp) aborted with vthread.cc: bool of_JOIN_DETACH(...): Assertion child->wt_context==0 || thr->wt_context!=child->wt_context failed when a task automatic (called from an initial block) started a fork begin #d ...; $finish; end join_none and then went on with its own delay. Stdout was lost in the abort, so the log stops early and points nowhere near the task. Making the task static (task win();, with its variables at module level) fixes it; the same code worked unchanged on a commercial simulator. Related gotcha found in the same test: $display("%0t", $time) prints in the global time precision (ps when any module is 1ns/1ps), not the module's unit; use %0d with $time when a log parser expects the module's unit.