In the process of looking into #77620, I noticed bugs in the
end-of-block detection functions in python.el.  If there is a comment
on the last line of the block, `python-info-statement-ends-block-p'
and `python-info-end-of-block-p' will not work correctly. 

Try the following Python code.

def func():
    return 0  # Comment

When the point is located after "0" of the return statement, both
`python-info-statement-ends-block-p' and `python-info-end-of-block-p'
return nil.  If there is no comment on the line, they return t as
expected.

This bug affects `python-nav-forward-sexp'.  In the above example, if
the point is located at the beginning of "def func()" line,
(python-nav-forward-sexp) moves the point to after "0".  This is the
expected behavior.

However, if we execute (python-nav-forward-sexp -1) there, it moves
the point to "0". This is not the expected behavior.  If there is no
comment, it moves the point to the beginning of "def func()" line.

Attached is a patch that fixes this problem.

--
In GNU Emacs 31.0.50 (build 8, x86_64-pc-linux-gnu, GTK+ Version
 3.24.41, cairo version 1.18.0) of 2025-01-01 built on ubuntu2404
Repository revision: 78bc5949db489b143f7424540d6cc56fc529c9ea
Repository branch: master
System Description: Ubuntu 24.04.2 LTS

Configured using:
 'configure --with-pgtk --with-native-compilation --with-tree-sitter'