PATCH: _tmux: Avoid breakages if `tmux' is not installed

[Frank Terbeck <ft@xxxxxxxxxxxxxxxxxxx>]

With this, _tmux will not attempt and sub-command completions if
tmux is not found in `$path'.

---

  I'm not entirely sure if this is the right thing to do[tm].

  Usually, you wouldn't expect people to try completions for programs
  they don't have installed, but apparently, some people do. ;-)

 Completion/Unix/Command/_tmux |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/Completion/Unix/Command/_tmux b/Completion/Unix/Command/_tmux
index e9977fb..5fb7219 100644
--- a/Completion/Unix/Command/_tmux
+++ b/Completion/Unix/Command/_tmux
@@ -1520,6 +1520,10 @@ function _tmux() {
                 _describe -t subcommands 'tmux commands and aliases' _tmux_commands -- _tmux_aliases
             fi
         else
+            if (( ${+commands[tmux]} == 0 )); then
+                _message '`tmux'\'' not found in $path; sub-cmd completions disabled.'
+                return 0
+            fi
             tmuxcommand="${words[1]}"
             if [[ -n ${_tmux_aliasmap[$tmuxcommand]} ]] ; then
                 tmuxcommand="${_tmux_aliasmap[$tmuxcommand]}"
-- 
1.7.5