git-rebase: Add a -v option to show a diffstat of the changes upstream at the start of a rebase.

Signed-off-by: Robert Shearman <rob@codeweavers.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/git-rebase.txt

@@ -7,7 +7,7 @@ git-rebase - Rebase local commits to a new head
 
 SYNOPSIS
 --------
-'git-rebase' [--merge] [--onto <newbase>] <upstream> [<branch>]
+'git-rebase' [-v] [--merge] [--onto <newbase>] <upstream> [<branch>]
 
 'git-rebase' --continue | --skip | --abort
 
@@ -121,6 +121,9 @@ OPTIONS
 	is used instead (`git-merge-recursive` when merging a single
 	head, `git-merge-octopus` otherwise).  This implies --merge.
 
+-v, \--verbose::
+	Display a diffstat of what changed upstream since the last rebase.
+
 include::merge-strategies.txt[]
 
 NOTES

git-rebase.sh

@@ -3,7 +3,7 @@
 # Copyright (c) 2005 Junio C Hamano.
 #
 
-USAGE='[--onto <newbase>] <upstream> [<branch>]'
+USAGE='[-v] [--onto <newbase>] <upstream> [<branch>]'
 LONG_USAGE='git-rebase replaces <branch> with a new branch of the
 same name.  When the --onto option is provided the new branch starts
 out with a HEAD equal to <newbase>, otherwise it is equal to <upstream>
@@ -39,6 +39,7 @@ strategy=recursive
 do_merge=
 dotest=$GIT_DIR/.dotest-merge
 prec=4
+verbose=
 
 continue_merge () {
 	test -n "$prev_head" || die "prev_head must be defined"
@@ -190,6 +191,9 @@ do
 		esac
 		do_merge=t
 		;;
+	-v|--verbose)
+		verbose=t
+		;;
 	-*)
 		usage
 		;;
@@ -273,6 +277,12 @@ then
 	exit 0
 fi
 
+if test -n "$verbose"
+then
+	echo "Changes from $mb to $onto:"
+	git-diff-tree --stat --summary "$mb" "$onto"
+fi
+
 # Rewind the head to "$onto"; this saves our current head in ORIG_HEAD.
 git-reset --hard "$onto"