Always copy Hash's default block on #dup and #clone

[HertzDevil]

When a hash is copied by either #dup or #clone, only compare_by_identity is copied but not the default block when the hash is empty:

hsh = Hash(Int32, String).new("")
hsh.compare_by_identity
hsh.dup.compare_by_identity? # => true
hsh.dup[0]                   # Missing hash key: 0 (KeyError)

hsh = Hash(Int32, String).new("")
hsh[1] = "a"
hsh.compare_by_identity
hsh.dup.compare_by_identity? # => true
hsh.dup[0]                   # => ""

Since the default block is part of the hash's internal state, it should always be copied even if the hash has no elements.

[asterite]

Great, thanks!

[caspiano]

you're an absolute don @HertzDevil!! thanks for the work you do for this language and community ❤️