Renames 314 defs and 41 module/class-level constants. Keeps 11 names underscored where the stripped form collides in scope, plus 5.5.0 shims for the three symbols external service repos call.
The rnet branch zeroed content_length only for gzip/deflate/br, so an
unknown coding (zstd, future tokens) kept a bogus length and, worse, the
drop-the-partial-instead-of-Range-resuming guard could never fire on the
rnet path because content_encoded stayed False. Use the same fail-closed
_is_content_encoded check the requests branch uses.
Reading .raw skips urllib3's decoding, so brotli-served subtitles landed compressed and converted to empty files. Also drops a partial rather than Range-resuming an encoded body, since a Range indexes the encoded bytes.
imSp4rky