[tmux] Gracefully handle different versions

tmux/.tmux.conf

@@ -43,7 +43,6 @@ bind -t vi-copy 'y' copy-selection
 ## etc
 set-window-option -g mode-keys vi
 set-option -sg escape-time 1 # increase vim responsiveness
-set-option -g renumber-windows on
 # set-option -g status-justify centre
 set-option -g base-index 1
 
@@ -55,8 +54,8 @@ set-option -g prefix C-a
 
 bind a send-prefix
 
-bind c new-window -c '#{pane_current_path}'
-bind C-c new-window -c '#{pane_current_path}'
+bind c new-window
+bind C-c new-window
 
 bind d detach
 bind C-d detach
@@ -69,8 +68,8 @@ bind C-p previous-window
 
 bind C-a last-window
 
-bind v split-window -h -c '#{pane_current_path}'
-bind s split-window -v -c '#{pane_current_path}'
+bind v split-window -h
+bind s split-window -v
 
 # bind h select-pane -L
 # bind j select-pane -D
@@ -91,6 +90,13 @@ bind -r - resize-pane -D 3
 bind -r + resize-pane -U 3
 bind -r = resize-pane -U 3
 
+if-shell "[[ `tmux -V` == *1.9 ]]" \
+  "set-option -g renumber-windows on" \
+  "bind c new-window -c '#{pane_current_path}'" \
+  "bind C-c new-window -c '#{pane_current_path}'" \
+  "bind v split-window -h -c '#{pane_current_path}'" \
+  "bind s split-window -v -c '#{pane_current_path}'"
+
 unbind r
 bind r source-file ~/.tmux.conf \; display 'Reloaded tmux.conf'