[PATCH] gitk: use the 'reference' format for the commit reference

[Beat Bolli <dev+git@xxxxxxxxx>]

Since 1f0fc1db85 (pretty: implement 'reference' format, 2019-11-19) in
the main Git repository, there's an officially blessed format for commit
references. Update gitk to also use this format.

Signed-off-by: Beat Bolli <dev+git@xxxxxxxxx>
---
 gitk | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/gitk b/gitk
index da84e22..b26996c 100755
--- a/gitk
+++ b/gitk
@@ -9433,8 +9433,7 @@ proc mktaggo {} {
 proc copyreference {} {
     global rowmenuid autosellen
 
-    set format "%h (\"%s\", %ad)"
-    set cmd [list git show -s --pretty=format:$format --date=short]
+    set cmd [list git show -s --pretty=reference]
     if {$autosellen < 40} {
         lappend cmd --abbrev=$autosellen
     }
-- 
2.26.0.277.gb8618d28a9