Remove binding that causes crash on OS X using current tmux

tmux.conf

@@ -66,16 +66,12 @@ bind p paste-buffer
 bind -t vi-copy 'v' begin-selection
 bind -t vi-copy 'y' copy-selection
 
+set-option -g default-command "reattach-to-user-namespace -l bash"
+
 # integrate with system clipboard
 bind C-c run 'tmux save-buffer - | xclip -i -sel clipboard'
 bind C-v run "tmux set-buffer \"$(xclip -o -sel clipboard)\"; tmux paste-buffer"
 
-# Make current pane into it's own temp window
-unbind Up
-bind Up new-window -d -n tmp \; swap-pane -s tmp.1 \; select-window -t tmp
-unbind Down
-bind Down last-window \; swap-pane -s tmp.1 \; kill-window -t tmp
-
 # Make switch session shortcut repeatable
 bind -r ( switch-client -p
 bind -r ) switch-client -n