Refactor another time.

autoload/vundle.vim

@@ -58,8 +58,8 @@ endif
 
 func! vundle#rc(...) abort
   let g:bundle_dir = len(a:000) > 0 ? expand(a:1, 1) : expand('$HOME/.vim/bundle', 1)
-  let g:bundles = []
   let g:updated_bundles = []
   let g:vundle_log = []
   let g:vundle_changelog = ['Updated Plugins:']
+  call vundle#config#init()
 endf

autoload/vundle/config.vim

@@ -7,6 +7,12 @@ func! vundle#config#bundle(arg, ...)
   return bundle
 endf
 
+func! vundle#config#init()
+  if !exists('g:bundles') | let g:bundles = [] | endif
+  call s:rtp_rm_a()
+  let g:bundles = []
+endf
+
 func! vundle#config#require(bundles) abort
   for b in a:bundles
     call s:rtp_add(b.rtpath)