I am glad that my report is helpful.
Thanks for your praise. :)

2018-03-14 10:45 GMT+08:00 Assaf Gordon <assafgordon@gmail.com>:
Hello,

On Tue, Mar 13, 2018 at 06:02:05PM +0800, 0xddaa wrote:
> There is the Proof-of-Concept:
>
> # echo z | sed 's/z/\x5c/' # \x5c == '\'
> \ # success
> # echo z | sed 's/z/\x5c\x61/'
> a # backslash is gone
>
> According the manual, *\xxx* should produce an ascii character. sed should
> not treat *\x5c* as an escape symbol.

Thank you for reporting this issue with such clear details
and providing a bug fix - much appreciated!

I expanded your fix by adding tests and news item, see attached patch.

There is a small issue that this is a backwards incompatible change,
and might break some exotic (bad) scripts.

I'll wait for other opinions before pushing this.

Jim,
What do you think?

regards,
 - assaf