commit-msg: Update the commit message hook

This version fixes a bug where Change-Id lines become the subject
line, if the subject used a pattern like the subject of this
message does.

Change-Id: I7f7e0363091d03eb05dead2992fc19763214de65
Signed-off-by: Shawn O. Pearce <sop@google.com>

hooks/commit-msg

@@ -1,4 +1,22 @@
 #!/bin/sh
+# From Gerrit Code Review v2.0.18-100-g98fc90a
+#
+# Part of Gerrit Code Review (http://code.google.com/p/gerrit/)
+#
+# Copyright (C) 2009 The Android Open Source Project
+# 
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+# 
+# http://www.apache.org/licenses/LICENSE-2.0
+# 
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# 
 
 MSG="$1"
 
@@ -13,8 +31,12 @@ add_ChangeId() {
 	id=$(_gen_ChangeId)
 	out="$MSG.new"
 	ftt="$MSG.footers"
-	sed -e  '/^[A-Za-z][A-Za-z0-9-]*: /,$d' <"$MSG" >"$out"
-	sed -ne '/^[A-Za-z][A-Za-z0-9-]*: /,$p' <"$MSG" >"$ftt"
+	sed -e  '2,${
+			/^[A-Za-z][A-Za-z0-9-]*: /,$d
+		}' <"$MSG" >"$out"
+	sed -ne '2,${
+			/^[A-Za-z][A-Za-z0-9-]*: /,$p
+		}' <"$MSG" >"$ftt"
 	if ! [ -s "$ftt" ]
 	then
 		echo >>"$out"