get rid of the code for compatibility with an unreleased version of bookdown

Author: yihui

R/render.R

@@ -81,10 +81,6 @@ render_book = function(
   )
 
   aux_diro = '_bookdown_files'
-  # for compatibility with bookdown <= 0.0.64
-  if (isTRUE(dir_exists(aux_dir2 <- file.path(output_dir, aux_diro)))) {
-    if (!dir_exists(aux_diro)) file.rename(aux_dir2, aux_diro)
-  }
   # move _files and _cache from _bookdown_files to ./, then from ./ to _bookdown_files
   aux_dirs = files_cache_dirs(aux_diro)
   move_dirs(aux_dirs, basename(aux_dirs))