YANG 1.1 modules allow unquoted strings with a quote character inside it

[binarycow]

RFC 7950 states:

An unquoted string cannot contain any single or double quote characters. This is a backward-incompatible change from YANG version 1. When updating a YANG version 1 module to 1.1 and the module uses such quote characters, the string must be changed to match the new rules. See Section 6.1.3 for details.

But the below module validates in pyang with no issues:

module charlie {
    namespace urn:charlie;
    prefix c;
    yang-version 1.1;

    container foo {
        description won't;
    }
}

validated with:

pyang -f flatten --flatten-description --flatten-keyword --strict charlie.yang