Hmm... going to have to get help here. I'm not familiar enough with this code or its expected output to really tell when it's working or when I might introduce a subtle bug somewhere. This seems more like the latter scenario. Thanks for pointing this out!
On this particular example, I'm not understanding how the two things are identical. The substitution pattern in your version has one less \05. Is that intentional? If so, how does that work? I don't really grok the look-around assertion, and/or how that's relevant to not needing the extra \05 in the substitution pattern.
For that matter, I'm not sure what \05 even is. Most places seem to say that an octal character code requires exactly 3 digits, but some say you can get away with less, as long as the leading digit is zero. But, \05 interpreted as octal is non-printing... don't know what it is, or why it would be in these files. Any thoughts on that?