REPL: Don't print the line that produced a `SyntaxWarning` if only a single line was given as input

Feature or enhancement

Bug description:

The old REPL had this behaviour:

~/dev/cpython (main)⚡ % PYTHON_BASIC_REPL=1 ./python.exe
Python 3.14.0a0 (heads/main:4606eff0aa, Jul 23 2024, 20:19:47) [Clang 15.0.0 (clang-1500.3.9.4)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> False is 0
<stdin>-0:1: SyntaxWarning: "is" with 'int' literal. Did you mean "=="?
False

The new one has this behaviour:

~/dev/cpython (main)⚡ % ./python.exe                             
Python 3.14.0a0 (heads/main:4606eff0aa, Jul 23 2024, 20:19:47) [Clang 15.0.0 (clang-1500.3.9.4)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> 0 is False
<python-input-0>:1: SyntaxWarning: "is" with 'int' literal. Did you mean "=="?
  0 is False
False

The new behaviour seems better if you've given a multiline function as input since, unlike the old REPL, it tells you exactly which line of code produced the warning:

~/dev/cpython (main)⚡ % ./python.exe
Python 3.14.0a0 (heads/main:4606eff0aa, Jul 23 2024, 20:19:47) [Clang 15.0.0 (clang-1500.3.9.4)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> def foo():
...     0 is False
...     3 == 4
...     
<python-input-0>:2: SyntaxWarning: "is" with 'int' literal. Did you mean "=="?
  0 is False

...but it feels a bit redundant if, as in my first example, only a single line was entered as input. It took me a little while to figure out why the REPL was just printing the line I had typed back at me.

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS

Inizia riproducendo gli esempi su una singola riga e su più righe nel nuovo CPython REPL e confronta il relativo output di SyntaxWarning. Leggi il percorso di visualizzazione degli avvisi del REPL, quindi fai in modo che il caso su una singola riga ometta il codice sorgente riecheggiato, preservando la riga sorgente per l'input su più righe; verifica entrambi i comportamenti con test REPL mirati.