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

首先在新的 CPython REPL 中重现单行和多行示例，并比较它们的 SyntaxWarning 输出。阅读 REPL 的警告显示路径，然后让单行情况省略回显的源代码，同时为多行输入保留源代码行；使用有针对性的 REPL 测试验证这两种行为。