upstart script. shell arithmetic in script stanza producing incorrect values. equivalent /bin/sh script works - sh

Question

I have an upstart init script, but my dev/testing/production have different numbers of cpus/cores. I'd like to compute the number of worker processes to be 4 * number of cores within the init script
The upstart docs say that the script stanzas use /bin/sh syntax.
I created /bin/sh script to see what was going on. I'm getting drastically different results than my upstart script.
script stanza from my upstart script:
script
# get the number of cores
CORES=`lscpu | grep -v '#' | wc -l`
# set the number of worker processes to 4 * num cores
WORKERS=$(($CORES * 4))
echo exec gunicorn -b localhost:8000 --workers $WORKERS tutalk_site.wsgi > tmp/gunicorn.txt
end script
which outputs:
exec gunicorn -b localhost:8000 --workers 76 tutalk_site.wsgi
my equivalent /bin/sh script
#!/bin/sh
CORES=`lscpu -p | grep -v '#' | wc -l`
WORKERS=$(($CORES * 4))
echo exec gunicorn -b localhost:8000 --workers $WORKERS tutalk_site.wsgi
which outputs:
exec gunicorn -b localhost:8000 --workers 8 tutalk_site.wsgi
I'm hoping this is a rather simple problem and a few other pairs of eyes will locate the issue.
Any help would be appreciated.

Answer 1

I suppose I should have answered this several days ago. I first attempted using environment variables instead but didn't have any luck.
I solved the issue by replacing the computation with a python one-liner
WORKERS=$(python -c "import os; print os.sysconf('SC_NPROCESSORS_ONLN') * 2")
and that worked out just fine.
still curious why my bourne-shell script came up with the correct value while the upstart script, whose docs say use bourne-shell syntax didn't