swift: fix python syntax error in ganglia stats

This was a silly error but Jenkins didn't catch it as it's not a .py.
The script is so broken, though, that Jenkins would complain about all
of its other errors, so let's avoid this for now... Hopefully next time
I'll touch this, I'll just rewrite it :)

Change-Id: I5e3a93d2d5e62fb7c1f488cff4f4b0982148a534