BUG REPORT: nntp-marks-file-name is reset to nil and causes "error IO error reading [...]: Is a directory"

[Teemu Likonen]

On 2009-08-16 21:08 (+0300), Teemu Likonen wrote:

> I have tried to use Gnus agent a couple of times but so far it hasn't
> been exactly a pleasant experience. I have pretty much default settings
> and all my nntp servers are agentized. Now, in Group buffer I go plugged
> (Jj), check new news (g), download them (Js) and go unplugged (Jj)
> again. Fine.
>
> Then I enter some group and read news. When exiting from the Summary
> buffer it gives me ugly error messages (see below). I answered "yes" to
> both of those questions and got back to Group buffer. Can I get rid of
> those errors? Looks like there's a bug in Gnus.
>
>
> Error reading nntp marks file
> /home/dtw/News/marks/news.inet.fi/comp/os/linux/misc/ ((error IO error
> reading /home/dtw/News/marks/news.inet.fi/comp/os/linux/misc/: Is a
> directory)). Continuing will use marks from .newsrc.eld.
> Continue? (yes or no)
>
> Could not write to /home/dtw/News/marks/news.inet.fi/comp/os/linux/misc/
> ((file-error Opening output file is a directory
> /home/dtw/News/marks/news.inet.fi/comp/os/linux/misc/)).
> Continue? (yes or no)

Here's more info: It's file lisp/gnus/nntp.el, function nntp-open-marks
and form (condition-case ...) where the error happens.

The reason for error is that variable nntp-marks-file-name is nil. It's
normally ".marks" (in my system too) but something sets it to nil when I
go unplugged with Jj (gnus-agent-toggle-plugged) command. Since the
variable is nil function nntp-group-pathname doesn't return complete
path with filename but only a directory name, hence the error in reading
the file: "error IO error reading [...]: Is a directory".

Clearly there's a but somewhere. Who is setting nntp-marks-file-name to
nil and why?