gitconfig/rebase.sh: adapt default branch name

Whatever it is, it likely won't be cros/chromeos-2013.04 anymore.

Change-Id: I020b65a7406e3bef7d1c8fad8c530354b1f78819
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/11438
Reviewed-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Tested-by: build bot (Jenkins)
1 file changed