bug#64406: [PATCH] Improve commands to manage Python imports

[Eli Zaretskii <eliz@gnu.org>]

> From: Matthias Meulien <orontee@gmail.com>
> Date: Sat, 01 Jul 2023 22:16:28 +0200
> 
> Commands python-add-import, python-remove-imports and
> python-sort-imports run a short Python script stored in variable
> python--list-imports; That script starts with:
> 
>     from isort import find_imports_in_stream, find_imports_in_paths
> 
> But find_imports_in_stream and find_imports_in_paths were introduced in
> version 5.7.0 of the isort library.
> 
> Debian bookworm has isort version 5.6.4 in its package repositories.
> Thus on such system commands python-add-import, python-remove-import
> and python-sort-imports fail with error message:
> 
>     python exited with status 1 (maybe isort is missing?)
> 
> This is misleading when the isort library is installed.
> 
> I suggest to extend the Python script in order to catch the import
> errors and return status 1 if the isort library is not found and status
> 2 if the expected symbols aren't found.  The error message can then be
> specialized.  This is what I implemented in the attached patch.

Thanks, installed on the master branch and closing the bug.