In 3.6.x, zombie corpses were always aged an extra 100:
NetHack/src/mon.c
Line 375 in 23d331a
obj->age -= 100; /* this is an *OLD* corpse */
in 5.0.x, zombie corpses are always aged TAINT_AGE, which is only 50:
NetHack/src/mon.c
Line 648 in 97a6c13
obj->age -= (TAINT_AGE + 1); /* this is an *OLD* corpse */
This is the result of commit 408321b.
The accompanying comment states that the purpose of that patch was meant to
just replace hard-coded numbers with symbolic values, but the commit set
two differing numeric values to the same symbol name, thus causing the
regression reported in:
https://github.com/NetHack/NetHack/issues/1664
Revert the values to match those of 3.6, and add the additional symbolic value.
Closes#1664