The author uses Debian OS packages and he's talking about installing one unpackaged dependency. He's relying on what's packaged in OS and is tested with other p

The author uses Debian OS packages and he's talking about installing one unpackaged dependency. He's relying on what's packaged in OS and is tested with other packages. He clearly doesn't want to get random dump of dependencies on every installation (given you leave version empty in requirements.txt). Basically, he's relying on Debian for QA of packages. I do the same. I don't need to track versions of gazillion of dependencies for every little Python thing I write. I just install it in the OS and use it from anywhere else.