The mailing list thread to bug tracking system problem
I will start with the thesis: open source projects would benefit from a canonical and easy way to take a mailing list message or thread and turn it into an issue or bug report in your bug tracking system.
It's entirely natural and rather normal for a but report to start with someone uncertainly asking 'is this supposed to happen?' or 'am I understanding this right?' questions on one of your mailing lists. They're not necessarily doing this because they don't know where to report bugs; often they may be doing it because they're not sure that what they're seeing is a bug (or at least a new bug), or they don't know how to file what your project considers a good bug report, and they don't want to take the hit of a bad bug report. It's usually easier to ask questions on a mailing list where some degree of ignorance is expected and accepted than to venture into what can be a sharp-edged swamp of a bug tracker.
If the requester is energetic, they'll jump through a lot of extra hoops to actually file a bug report once they've built up their confidence (or just been pointed to the right place). But in general, the more difficult the re-filing process is the fewer bug reports you're going to get, while the easier it is the more you'll get.
This leads me to my view that most open source projects make this too hard today, usually by having no explicit way to do it because their mailing list systems and bug tracking systems are completely separate things. Maybe this separation can be overcome through cultural changes so that brief pointers to mailing list messages or cut and paste copies from mailing list threads become acceptable as bug reports.
(My impression, perhaps erroneous, is that most open source projects want you to rewrite your bug reports from more or less scratch when you make them. The mailing list is the informal version of your report, the bug tracker gets the 'formal' one. Of course the danger here is that people just don't bother to write the formal version for various reasons.)
PS: I admit that one reason I've wound up feeling this way is that I'm currently sitting on a number of issues that I first raised on mailing lists and still haven't gotten around to filing bug reports for. And by now some of them are old enough that I'd have to reread a bunch of stuff just to recover the context I had at the time and understand the whole problem once again.