Linking directly to the Git repo can lead to bad things, this being one of them. Ruby has rubygems, a managed version-ed dependency system that is one layer removed from source control. Does python have a system like Rubygems?
I suppose this is one of the great advantages of CPAN being developed in the era of modem based internet :)
It's surprising how little known these things are - compared to e.g. Ruby Gems, CPAN, CTAN, CRAN and npm.
There's a few command-line programs to access it from, the most popular right now being "pip".
In general, you should mirror external dependencies to the extent you're risk-averse. Mildly paranoid startup? Fork any github repos that might disappear and that don't already have forks you trust. Running a large financial institution? Run your own gem server, apt repo, etc.