* zlib: clear unconsumed_tail when a bounded decompress reaches stream end
When a max_length-bounded Decompress.decompress() call reached the end
of the stream, the bytes after the stream went to unused_data, but
unconsumed_tail kept the previous call's tail, including input the call
had already consumed. A later flush() then moved those stale bytes into
unused_data.
Empty unconsumed_tail at end of stream, as CPython's
save_unconsumed_input() does since gh-158169. CPython releases before
that change report the bytes after the stream in unconsumed_tail, so
the snippet accepts either value when it runs under CPython.
Fixes#8906
Assisted-by: Claude Code:claude-opus-5-5
* zlib: bind the unconsumed input with an if expression
Choose between the empty slice and the rest of the input in one
expression instead of reassigning a mutable binding.
Assisted-by: Claude Code:claude-opus-5-5
* zlib: accept both valid tails in the snippet on every implementation
The snippet no longer branches on sys.implementation. RustPython and
CPython after gh-158169 give an empty tail; CPython before it gives the
bytes after the stream. The stale tail of gh-8906 fails either way.
Assisted-by: Claude Code:claude-opus-5-5
Jean-Marc Le Roux