Mash dist -p, wrong number of threads (bug?)

[d-golzato]

Hi developers,

thanks for this tool. I've installed version 2.3 and noticed that mash dist -p 1 actually spawns about 8 threads instead of 1.
I've checked the -p parameter with versions 1.1 and 2.0 and it seems that from version 2.0 mash spawns more threads than
the number specified (1, in my case).

I've checked the documentation and didn't find anything about this, can you please provide some insights?

Thank you,

Davide