omf.destroy: find the most recent backup of config.

 using XDG_CONFIG_HOME

pkg/omf/cli/omf.destroy.fish

@@ -5,8 +5,15 @@ function omf.destroy -d "Remove Oh My Fish"
     omf.remove_package $pkg >/dev/null ^&1
   end
 
-  if test -e "$HOME/.config/fish/config.copy"
-    mv "$HOME/.config/fish/config".{copy,fish}
+  set -l fish_config $XDG_CONFIG_HOME/fish
+  if test "$fish_config" = "/fish"
+    set fish_config $HOME/.config/fish
+  end
+
+  set -l localbackup (find $fish_config -regextype posix-extended -regex '^.*fish/config\.[[:digit:]]+\.copy$' |\
+    sort -r |head -1)
+  if test -n $localbackup
+    mv $localbackup "$fish_config/config.fish"
   end
 
   if test "$OMF_PATH" != "$HOME"