made run() generate an environment for stuff it runs

modules/lib/shutil.lua

@@ -29,7 +29,7 @@ function loadfile(fn)
  local f=io.open(fn,"rb")
  local S=f:read("*a")
  f:close()
- return load(S)
+ return load(S,"=("..fn..")","bt",os.genenv())
 end
 function run(fn,...)
  local r = {pcall(loadfile(fn),...)}