The set body is user-supplied and commonly JSON, but it was expanded with
ReplaceAll, which blanks any {...} the replacer does not recognize, so a
plain JSON body was sent empty and a body mixing JSON with a real
placeholder was mangled
Use ReplaceKnown, matching the respond body, so unrecognized braces are
left intact and real placeholders still expand. Regression test pins both
directions
Co-authored-by: hktitof <hktitof@users.noreply.github.com>
