[PATCH] gitk: handle external diff tool with spaces in the path

[Pat Thoyts <patthoyts@users.sourceforge.net>]

  This fixes the launching of external diff to handle a diff tool
  that has spaces in the path. This patch ensures a correctly formed
  tcl list is passed to the open command with a single pipe character
  prefixing the list (as per the tcl manual page for open).

  The specific fault observed was that selecting WinMerge as the diff
  tool from the default installed location in Program Files failed to
  be launched from the context menu.

Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>
---
 gitk |    5 ++---
 1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/gitk b/gitk
index edb3ba2..656c2c1 100755
--- a/gitk
+++ b/gitk
@@ -3237,9 +3237,8 @@ proc external_diff {} {
     set difftofile [external_diff_get_one_file $diffidto $flist_menu_file $diffdir]
 
     if {$difffromfile ne {} && $difftofile ne {}} {
-        set cmd [concat | [shellsplit $extdifftool] \
-		     [list $difffromfile $difftofile]]
-        if {[catch {set fl [open $cmd r]} err]} {
+        set cmd [list [shellsplit $extdifftool] $difffromfile $difftofile]
+        if {[catch {set fl [open |$cmd r]} err]} {
             file delete -force $diffdir
             error_popup "$extdifftool: [mc "command failed:"] $err"
         } else {
-- 
1.6.2.2.1669.g7eaf8