Release X.Y (202?-??-??)

Two new builtin functions, builtins.parseFlakeRef and builtins.flakeRefToString, have been added. These functions are useful for converting between flake references encoded as attribute sets and URLs.
builtins.toJSON now prints --show-trace items for the path in which it finds an evaluation error.
Error messages regarding malformed input to derivation add are now clearer and more detailed.
The discard-references feature has been stabilized. This means that the unsafeDiscardReferences attribute is no longer guarded by an experimental flag and can be used freely.
The JSON output for derived paths with are store paths is now a string, not an object with a single path field. This only affects nix-build --json when "building" non-derivation things like fetched sources, which is a no-op.
Introduce a new outputOf builtin. It is part of the dynamic-derivations experimental feature.
Flake follow paths at depths greater than 2 are now handled correctly, preventing "follows a non-existent input" errors.