Adding >1 new line within a codeblock doesn't correctly match the indentation

[aelsayed95]

Bug report

Bug description:

Adding more than one new line within a codeblock doesn't correctly match the indentation the previous line's indentation:

For example if I start with the following codeblock:

>>> def f():
... 
... a = 1
>>>

and modify it to add two additional new lines in-block, I end up with the following:

>>> def f():
... 
... 
... 
... a = 1
... 
>>>

Note that now, lines 2,5 have indentation, but lines 3 and 4 have no indentation.
This doesn't match IPython's behaviour.

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS

[savannahostrowski]

In case it's helpful, this is also reproducible on Fedora, using the Devcontainer configuration in the repo.

[lysnikolaou]

Thanks for the issue @aelsayed95 and the confirmation @savannahostrowski!

This was fixed in #119606. Feel free to reopen in case you encounter this again.