Weird "border" with jpegtran when rotating an image - libjpeg-turbo

Question

I'm using jpegtran to rotate my images, but it seems to be doing some weird stuff.
The same code/logic worked on my other server. Here is a test case I've done:
test.jpg is the original image, then I run:
jpegtran -rotate 90 test1.jpg > test2.jpg.tmp
mv test2.jpg.tmp test2.jpg
jpegtran -rotate 90 test2.jpg > test3.jpg.tmp
mv test3.jpg.tmp test3.jpg
test.jpg:
test2.jpg
test3.jpg:
As you should be able to see, there are weird borders on it (almost like shadows on another part of the image):
What would cause this, and how can I get around it?
The OLD server shows:
jpegtran -v
libjpeg-turbo version 1.2.1 (build 20131209)
Copyright (C) 1991-2010 Thomas G. Lane, Guido Vollbeding
Copyright (C) 1999-2006 MIYASAKA Masaru
Copyright (C) 2009 Pierre Ossman for Cendio AB
Copyright (C) 2009-2012 D. R. Commander
Copyright (C) 2009-2011 Nokia Corporation and/or its subsidiary(-ies)
Emulating The Independent JPEG Group's libjpeg, version 6b 27-Mar-1998
...and the NEW server shows:
jpegtran -v
Independent JPEG Group's JPEGTRAN, version 9b 17-Jan-2016
Copyright (C) 2016, Thomas G. Lane, Guido Vollbeding

Answer 1

Typically, no sooner had I written the question out and posted it, I found the solution :)
http://www.imagemagick.org/discourse-server/viewtopic.php?t=21341#p87099
Basically, to add "-trim" to the command - so it looks like:
jpegtran -rotate 90 -trim test1.jpg > test2.jpg.tmp
mv test2.jpg.tmp test2.jpg
jpegtran -rotate 90 -trim test2.jpg > test3.jpg.tmp
mv test3.jpg.tmp test3.jpg
I've just tried this out, and it works as expected :) Thought I would post it here in case anyone else comes across this!