git-gui: Teach sign off to be more intelligent.

When we sign off on a commit we want to add a blank line between
whatever is in the commit buffer and the new Signed-off-by line,
unless there already is a Signed-off-by (or Acked-by) tag at the end
of the buffer already.  This change makes us do the right thing more
often.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

diff --git a/git-gui b/git-gui
index 9a259c0..8a42c97 100755 (executable)
--- a/git-gui
+++ b/git-gui
@@ -1510,10 +1510,15 @@ proc do_signoff {} {
                }
        }
 
-       set str "Signed-off-by: $GIT_COMMITTER_IDENT"
-       if {[$ui_comm get {end -1c linestart} {end -1c}] != $str} {
+       set sob "Signed-off-by: $GIT_COMMITTER_IDENT"
+       set last [$ui_comm get {end -1c linestart} {end -1c}]
+       if {$last != $sob} {
                $ui_comm edit separator
-               $ui_comm insert end "\n$str"
+               if {$last != {}
+                       && ![regexp {^[A-Z][A-Za-z]*-[A-Za-z-]+: *} $last]} {
+                       $ui_comm insert end "\n"
+               }
+               $ui_comm insert end "\n$sob"
                $ui_comm edit separator
                $ui_comm see end
        }