rebase: don't source git-sh-setup twice

The git-sh-setup script is already sourced in git-rebase.sh before
calling into git-rebase--(am|interactive|merge).sh. There are no other
callers of these scripts. It is therefore unnecessary to source
git-sh-setup again in them.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-rebase--am.sh

@@ -3,8 +3,6 @@
 # Copyright (c) 2010 Junio C Hamano.
 #
 
-. git-sh-setup
-
 case "$action" in
 continue)
 	git am --resolved --resolvemsg="$resolvemsg" &&

git-rebase--interactive.sh

@@ -9,9 +9,7 @@
 #
 # The original idea comes from Eric W. Biederman, in
 # http://article.gmane.org/gmane.comp.version-control.git/22407
-
-. git-sh-setup
-
+#
 # The file containing rebase commands, comments, and empty lines.
 # This file is created by "git rebase -i" then edited by the user.  As
 # the lines are processed, they are removed from the front of this

git-rebase--merge.sh

@@ -3,8 +3,6 @@
 # Copyright (c) 2010 Junio C Hamano.
 #
 
-. git-sh-setup
-
 prec=4
 
 read_state () {