Error in descriptor download log message
When we only launch one descriptor download in the basic-min
chutney network, we add one extra descriptor to the "n at a time" part of the log message. (There are only 3 descriptors in this network.)
Jul 08 12:30:51.000 [info] launch_descriptor_downloads: Launching 1 request for 3 microdescs, 4 at a time