Merge pull request #4754 from myk002/myk_unbreak_luacov

[Core] don't harden Lua io.popen if Lua coverage monitoring is enabled

Author: myk002

library/LuaTools.cpp

@@ -1898,11 +1898,13 @@ lua_State *DFHack::Lua::Open(color_ostream &out, lua_State *state)
     luaL_setfuncs(state, dfhack_coro_funcs, 0);
     lua_pop(state, 1);
 
-    // replace some io functions
-    lua_getglobal(state, "io");
-    lua_pushnil(state);
-    lua_setfield(state, -2, "popen");
-    lua_pop(state, 1);
+    // remove some io functions (if coverage monitoring, which needs them, is not enabled)
+    if (!getenv("DFHACK_ENABLE_LUACOV")) {
+        lua_getglobal(state, "io");
+        lua_pushnil(state);
+        lua_setfield(state, -2, "popen");
+        lua_pop(state, 1);
+    }
 
     // replace some os functions
     lua_getglobal(state, "os");