Add hook that checks the commit message for hints it should be split.

Signed-off-by: Benjamin C Meyer <ben@meyerhome.net>

diff --git a/contrib/commit-msg/multiple-commits b/contrib/commit-msg/multiple-commits
new file mode 100755 (executable)
index 0000000..28572e4
--- /dev/null
+++ b/contrib/commit-msg/multiple-commits
@@ -0,0 +1,45 @@
+#!/bin/bash
+#
+# Copyright (c) 2010-2012, Benjamin C. Meyer <ben@meyerhome.net>
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are met:
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in the
+#    documentation and/or other materials provided with the distribution.
+# 3. Neither the name of the project nor the
+#    names of its contributors may be used to endorse or promote products
+#    derived from this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER ''AS IS'' AND ANY
+# EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+# DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
+# DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+# LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+# ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#
+
+function run_test
+{
+    warnings=$(cat "${1}" | egrep -i "(also|while here|^And)")
+    if [ ! -z "${warnings}" ] ; then
+        echo >&2 "This commit message hints that this commit might contain multiple different fixes that should be split into their own commit."
+        echo -e >&2 "\t"${warnings}"";
+    fi
+}
+
+case "${1}" in
+    --about )
+        echo -n "Check the commit message for hints that the commit contains multiple fixes: "
+        ;;
+    * )
+        run_test "$@"
+        ;;
+esac