Removing rake autocompletion as this is apparently baked into recent versions of zsh

lib/rake_completion.zsh

-_rake_does_task_list_need_generating () {
-  if [ ! -f .rake_tasks~ ]; then return 0;
-  else
-    accurate=$(stat -f%m .rake_tasks~)
-    changed=$(stat -f%m Rakefile)
-    return $(expr $accurate '>=' $changed)
-  fi
-}
-
-_rake () {
-  if [ -f Rakefile ]; then
-    if _rake_does_task_list_need_generating; then
-      echo "\nGenerating .rake_tasks~..." > /dev/stderr
-      rake --silent --tasks | cut -d " " -f 2 > .rake_tasks~
-    fi
-    compadd `cat .rake_tasks~`
-  fi
-}
-
-compctl -K _rake rake
-
 function _cap_does_task_list_need_generating () {
   if [ ! -f .cap_tasks~ ]; then return 0;
   else