This map has always been broken. This variant makes it slightly less broken (although something changed on the ceiling might prevent hiding on pixels on the slope). What will finally fix it is either moving nets closer together or adding angle bounce to hedgehogs or some other layout that prevents hiding.
/*
** $Id: lstring.h,v 1.43.1.1 2007/12/27 13:02:25 roberto Exp $
** String table (keep all strings handled by Lua)
** See Copyright Notice in lua.h
*/
#ifndef lstring_h
#define lstring_h
#include "lgc.h"
#include "lobject.h"
#include "lstate.h"
#define sizestring(s) (sizeof(union TString)+((s)->len+1)*sizeof(char))
#define sizeudata(u) (sizeof(union Udata)+(u)->len)
#define luaS_new(L, s) (luaS_newlstr(L, s, strlen(s)))
#define luaS_newliteral(L, s) (luaS_newlstr(L, "" s, \
(sizeof(s)/sizeof(char))-1))
#define luaS_fix(s) l_setbit((s)->tsv.marked, FIXEDBIT)
LUAI_FUNC void luaS_resize (lua_State *L, int newsize);
LUAI_FUNC Udata *luaS_newudata (lua_State *L, size_t s, Table *e);
LUAI_FUNC TString *luaS_newlstr (lua_State *L, const char *str, size_t l);
#endif