gitk: Replace SHA1 entry field on keyboard paste

We already replace old SHA with the clipboard content for the mouse
paste event.  It seems reasonable to do the same when pasting from
keyboard.

Signed-off-by: Ilya Bobyr <ilya.bobyr@gmail.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

gitk

@@ -2585,6 +2585,7 @@ proc makewindow {} {
     bind $fstring <Key-Return> {dofind 1 1}
     bind $sha1entry <Key-Return> {gotocommit; break}
     bind $sha1entry <<PasteSelection>> clearsha1
+    bind $sha1entry <<Paste>> clearsha1
     bind $cflist <1> {sel_flist %W %x %y; break}
     bind $cflist <B1-Motion> {sel_flist %W %x %y; break}
     bind $cflist <ButtonRelease-1> {treeclick %W %x %y}