I want to use a recent fix in Mix (specifically Another attempt at fixing opening in browser on Windows · hexpm/hex@dd9c62b · GitHub) before the next elixir release arrives. I’ve looked through my installation directories (.asdf/installs/elixir/current/ on linux and ~\scoop\apps\elixir\current\ on windows) and have confused myself. I’ve browsed and ripgrepped and can’t find the relevant source. I realise I don’t have a good handle on how the default packages work so wouldn’t be sure what to do even if I do find it. So some questions from the general to the specific:

• is there a good general doc or description somewhere of how elixir packages relate to modules, and how module discovery and loading works? (in which case I might be able to answer the below questions myself).
• what are the source files (in [installdir]/lib) used for? I’m guessing they’re not locally compiled, given the presence of the presumably preinstalled *.beam files in [installdir]/lib/**/ebin?
• either way, can a preinstalled package be overriden locally? (eg. is there an equivalent of the order in a java classpath I can rely on, or can I edit and recompile one of the preinstalled modules in place?)
• how would I do this (whatever ‘this’ may turn out to be) for the Mix.Tasks.Hex.Docs in the quoted commit?

Answers to any or all alike much appreciated!