We set `core.fsmonitor` to `false` in #13586 because Git's fsmonitor
daemon prevented the release of our locks, resulting in errors for some
users reported in #13521.
However, the fix from #13586 set `core.fsmonitor` to `false` too often.
This is not needed for taps, or when `HOMEBREW_REPOSITORY` is different
from `HOMEBREW_PREFIX`. The issue in #13521 stems from the fsmonitor
daemon preventing the release of our locks, so there is no need to
prevent the daemon from monitoring repositories that don't contain our
lock files.
The main class you should look at is the {Formula} class (and classes linked from there). That's the class that's used to create Homebrew formulae (i.e. package descriptions). Assume anything else you stumble upon is private.
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