Starting from somewhere around GHC 7.8, Cabal installs packages with a
hashed package key instead of just "{NAME}-{VERSION}". In other words,
the pair of the plain package name and the version is no longer unique
in the package DB, and using it for uninstallation may also remove
packages that we didn't mean to remove.
This is paricularly problematic because GHC comes with several bundled
Cabal packages. Installing and uninstalling a package with the same
name could break GHC itself, if the uninstallation is performed
without hashed keys.
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