[PATCH] git-gui: respect commit.gpgsign again

As of v2.9.0, `git commit-tree` no longer heeds the `commit.gpgsign`
config setting. This broke committing in Git GUI.

This fixes https://github.com/git-for-windows/git/issues/850

Signed-off-by: Johannes Schindelin <redacted>
---
Published-As: https://github.com/dscho/git/releases/tag/git-gui-gpgsign-v1
Fetch-It-Via: git fetch https://github.com/dscho/git git-gui-gpgsign-v1

 git-gui/lib/commit.tcl | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/git-gui/lib/commit.tcl b/git-gui/lib/commit.tcl
index 864b687..01d2cc2 100644
--- a/git-gui/lib/commit.tcl
+++ b/git-gui/lib/commit.tcl

@@ -369,6 +369,9 @@ A rescan will be automatically started now.
 	# -- Create the commit.
 	#
 	set cmd [list commit-tree $tree_id]
+	if {[is_config_true commit.gpgsign]} {
+		lappend cmd -S
+	}
 	foreach p [concat $PARENT $MERGE_HEAD] {
 		lappend cmd -p $p
 	}

-- 
2.10.0.windows.1.10.g803177d

base-commit: 6ebdac1bab966b720d776aa43ca188fe378b1f4b