Issue with UTF-8 failing to decode hex bytes

[ghost]

Given the following raw hex string:

public constant notValid = hex"F09FA684";
Solidity throws the following error:

Type literal_string (contains invalid UTF-8 sequence at position 3) is not implicitly convertible to
expected type string memory.

However, given the valid series of UTF-8 encoded bytes \xF0\x9F\xA6\x84, Solidity should decode it to get the unicorn emoji: 🦄, a valid UTF-8 decoded character.

You can verify the desired behavior here,
entering \xF0\x9F\xA6\x84 into the UTF-8-encoded box.

This issue was discovered as the result of a StackExchange question, which you can find here .

Solidity 0.4.11
Related Files:
/libdevcore/UTF8.cpp [1071] - where error is thrown
/libsolidity/ast/Types.cpp [31] - validateUTF8() improperly returns false
OS: Ubuntu 16.04