Python interactive buffer showing completions of the empty string instead of regular output

Question

I am working with python code, and I would like to be able to evaluate it in an emacs buffer, rather than using another terminal window. I am working with the python-mode from python.el, bundled with emacs.

This works just fine with emacs 24.3 on two different computers (windows and linux). However, I cannot get it to work on a 4rd computer with emacs 24.4: after spawning the buffer, it only shows completion candidates for an empty string (even though I didn't ask for any completion), and if I send a string, be it from a python-mode buffer or directly in the comint buffer, it just shows this list of completions again, and not the result of the command.

What's even more troubling is that according to google results, I am the only one with this issue, yet it is out-of-the-box experience!

Here are some screenshots with emacs -Q:

Bottom of the output:

Top of the output:

I am using emacs 24.4.1 on linux, and the problem appears with both python 2.7.9 and python 3.4.1.

Any clue?

Edit 1 Thanks to Ista's answer, I was able to check that there is nothing different in my *Messages* or in the content of variables python-shell-interpreter, python-shell-interpreter-args, python-shell-completion-setup-code, python-ffap-setup-code or python-eldoc-setup-code when compared to a working setup.

Edit 2 Thanks to a comment by Ista, I tried with a new user, and the problem didn't appear! I have tried restoring various settings to default (notably desktop-wide shortcuts), but without success for now.

Edit 3 I also tried with the ipython interpreter, the result is the same.

Edit 4 I tried starting python from eshell, shell and term (line-mode), it has the same problem: when I enter 2+2; and press RET, I see a list of completions instead of 4. term with char-mode works fine.

Overall, it looks like emacs sends a <TAB> to the inferior process whenever it tries to interact with it.

Answer 1

Not an answer but posting here because it is too long for a comment.

That sounds very strange. Is there anything odd in your messages buffer after you start python? Here is what I see:

Making python-shell-interpreter local to *Python* while let-bound!
Making python-shell-interpreter-args local to *Python* while let-bound!
Sent python-shell-completion-setup-code
Sent python-ffap-setup-code
Sent python-eldoc-setup-code

and here are the contents of the mentioned variables:

python-shell-interpreter is a variable defined in `python.el'.
Its value is "python"

python-shell-interpreter-args is a variable defined in `python.el'.
Its value is "-i"

python-shell-completion-setup-code is a variable defined in `python.el'.
Its value is
"try:
    import readline, rlcompleter
except ImportError:
    def __PYTHON_EL_get_completions(text):
        return []
else:
    def __PYTHON_EL_get_completions(text):
        completions = []
        try:
            splits = text.split()
            is_module = splits and splits[0] in ('from', 'import')
            is_ipython = getattr(
                __builtins__, '__IPYTHON__',
                getattr(__builtins__, '__IPYTHON__active', False))
            if is_module:
                from IPython.core.completerlib import module_completion
                completions = module_completion(text.strip())
            elif is_ipython and getattr(__builtins__, '__IP', None):
                completions = __IP.complete(text)
            elif is_ipython and getattr(__builtins__, 'get_ipython', None):
                completions = get_ipython().Completer.all_completions(text)
            else:
                i = 0
                while True:
                    res = readline.get_completer()(text, i)
                    if not res:
                        break
                    i += 1
                    completions.append(res)
        except:
            pass
        return completions"
python-ffap-setup-code is a variable defined in `python.el'.
Its value is
"def __FFAP_get_module_path(module):
    try:
        import os
        path = __import__(module).__file__
        if path[-4:] == '.pyc' and os.path.exists(path[0:-1]):
            path = path[:-1]
        return path
    except:
        return ''"

python-eldoc-setup-code is a variable defined in `python.el'.
Its value is
"def __PYDOC_get_help(obj):
    try:
        import inspect
        if hasattr(obj, 'startswith'):
            obj = eval(obj, globals())
        doc = inspect.getdoc(obj)
        if not doc and callable(obj):
            target = None
            if inspect.isclass(obj) and hasattr(obj, '__init__'):
                target = obj.__init__
                objtype = 'class'
            else:
                target = obj
                objtype = 'def'
            if target:
                args = inspect.formatargspec(
                    *inspect.getargspec(target)
                )
                name = obj.__name__
                doc = '{objtype} {name}{args}'.format(
                    objtype=objtype, name=name, args=args
                )
        else:
            doc = doc.splitlines()[0]
    except:
        doc = ''
    try:
        exec('print doc')
    except SyntaxError:
        print(doc)"

Perhaps you can spot a difference between my settings and yours that might be causing the issue (these are the settings I have when starting with emacs -Q). You may also try running the code defined in python-shell-completion-setup-code, python-ffap-setup-code and python-eldoc-setup-code in python to see if they do something unexpected. Maybe you redefined one of the python functions called by them?

Answer 2

Investigating all my local settings finally gave the answer.

I had in my .inputrc (settings for readline, which is used by the interactive python interpreter) the line :

Control-j: menu-complete

I have no idea what it was supposed to do, but at least commenting it out fixed it.