regression in parameter expansion with backslash escaped strings

Hello,

dracut-ng reports an issue with dash 0.5.13.1, where parameter expansion 
of strings containing backslash-escaped sequences interprets the 
sequences. This behaviour was bisected to
776424a8f9158bfe9f53aa55f931af9f73437caf parser: Add dollar single quote

A simple reproducing case is:

#!/bin/sh

str_replace() {
     local in="$1"
     local s="$2"
     local r="$3"
     local out=''

     while [ "${in##*"$s"*}" != "$in" ]; do
         chop="${in%%"$s"*}"
         out="${out}${chop}$r"
         in="${in#*"$s"}"
     done
     printf -- '%s' "${out}${in}"
}

str_replace "/dev/disk/by-label/dracut" '/' '\x2f'
echo
_name=$(str_replace "/dev/disk/by-label/dracut" '/' '\x2f')
echo "_name=$_name"

In bash and dash 0.5.12, this produces:

\x2fdev\x2fdisk\x2fby-label\x2fdracut
_name=\x2fdev\x2fdisk\x2fby-label\x2fdracut

In dash 0.5.13.1, this produces:

\x2fdev\x2fdisk\x2fby-label\x2fdracut
_name=/dev/disk/by-label/dracut

Github issue: https://github.com/dracut-ng/dracut-ng/issues/2280

-- 
classabbyamp