New ref generates 8MB mail message

[Matthew Wilcox <matthew@wil.cx>]

There's a bit of an unfortunate mistake in the default mail script
that causes making a new ref for Linus' kernel tree to generate an 8MB
mail message.

Based on the idea that a new branch is probably a branch off master, and
if it isn't, then at least sending a log vs master is better than a log
vs the beginning of time, I propose this patch:

diff --git a/templates/hooks--update b/templates/hooks--update
index 6db555f..609b4fe 100644
--- a/templates/hooks--update
+++ b/templates/hooks--update
@@ -13,7 +13,7 @@ recipient="commit-list@example.com"
 if expr "$2" : '0*$' >/dev/null
 then
 	echo "Created a new ref, with the following commits:"
-	git-rev-list --pretty "$3"
+	git-rev-list --pretty "$3" ^master
 else
 	base=$(git-merge-base "$2" "$3")
 	case "$base" in