`b"\\\\" == b"\\"`, is this intended?

[jakobnissen]

Currently, we have

julia> b"\\\\" == b"\\"
true

Which I can't understand. Something adjecant is mentioned in the manual here: https://docs.julialang.org/en/v1/manual/strings/#man-raw-string-literals,
but this does not really cover why length(b"\\\\") == 1.

[simeonschaub]

Looks like backslashes here get unescaped twice, once in the parser and once when unescape_string is called inside @b_str. Somewhat related to #41041

[mgkuhn]

Duplicate of #39092, where I provide a detailed explanation of what happens.

[vtjnash]

It would probably be good to fix this, but breaking