[meta-raspberrypi] du giving non-integer result?

[Trevor Woerner <twoerner@gmail.com>]

I can't explain why, but when I build "core-image-minimal" for
MACHINE=raspberrpi2 I get the following SD creation error:

    ERROR: Error: The image creation script
    '/z/layerindex-master/raspi2/tmp/work/raspberrypi2-poky-linux-gnueabi/core-image-minimal/1.0-r0/temp/create_image.rpi-sdimg'
    returned 2:
    expr: non-integer argument
    WARNING:
    /z/layerindex-master/raspi2/tmp/work/raspberrypi2-poky-linux-gnueabi/core-image-minimal/1.0-r0/temp/create_image.rpi-sdimg:1
    exit 2 from
      ROOTFS_SIZE_ALIGNED=$(expr 12288.0 + 4096 - 1)


Looking at meta-raspberrypi/classes/sdcard_image-rpi.bbclass, line 83:

    ROOTFS_SIZE_ALIGNED=$(expr ${ROOTFS_SIZE} +
${IMAGE_ROOTFS_ALIGNMENT} - 1)

which looks like the offending line. ROOTFS_SIZE seems to come from the
line immediately above:

    ROOTFS_SIZE=`du -bks ${SDIMG_ROOTFS} | awk '{print $1}'`

But 'du' doesn't return non-integer values, does it? When I invoke the
host's 'du' I get the correct value:

    du -bks
/z/layerindex-master/raspi2/tmp/deploy/images/raspberrypi2/core-image-minimal-raspberrypi2-20150906234844.rootfs.ext3
| awk '{print $1}'
    12288

Does anyone have any idea why the ".0" is getting tacked on?

Best regards,
    Trevor