I linked to a group in external library… referenced it as a “dupligroup” using an empty… then deleted the empty.
But… the reference to the library is still there, with a (non-fake) user count of 1.
How do I get rid of it? There are no remaining references to the group (that I’m aware of) but Blender thinks there is one.
Bump…
Uhh, how do you “un-link” a library?
Right now, in the “File/Directory” view, none of the items in the library appear.
In the good ol’ OOPS-schematic window, the objects from that group are “over here,” and the objects in the main scene are “over there,” and there are no arcs linking them.
The “Outliner” view shows that it’s there, but is curiously-unhelpful. When I display “Libraries,” there is the library-path, with a black-colored “Li” icon beside it. Hovering the cursor over it does nothing. None of the objects from the library appear in this version (vs. OOPS).
How, then, do you … using Python or otherwise … un-link a library?
If the “owner count” is ‘1’, how can you determine who the owners are?
This strikes me as some kind of “dangling reference” but how do I clean it up?
:spin:
Well, I found it. :yes:
Now, let me tell you how I found it… It is actually very interesting.
(1) “The very strange thing about this” was that nothing was showing up in the Outliner view. As far as it was concerned, there were no references at all to the library. That is to say, no objects, at all, referred to it.
(2) This led me to the OOPS Schematic view, where I noticed that there was a group of blocks that indeed were not connected to anything. But I did not notice that the “Li” button at the bottom of that window was not-clicked. So, Library datablocks were not being displayed.
(3) When I “re-discovered” that button and clicked it, the Library block appeared and I could “Select Linked” … and all of the unexplained blocks promptly lit up. Once again, I could move them freely because they were not connected to any object. (I promptly mashed all those buttons, just to make sure that I wasn’t “failing to see” anything else. And I wasn’t…)
(4) :spin: “Waitaminnit… none of these things are objects. They’re all textures and materials.” (He said, pulling off his glasses squinting at the screen in the manner that you, too one day will do… :eek: …)
(5) In the other window, “Shift+F4” took me to the File Browser display… click “…” to go up, then down to Textures. Nothing unusual there… just a bunch of textures with a user-count of “1.”
(5a) Back “up,” then down to Materials and … bingo! Here, the display for those materials says: LF 1. - “L” = Linked. It comes from a library. Yeah, I know… - “1” = One user. Yeah, I know. That’s why it’s hangin’ around these parts. - “F” = Fake User!" 
Eureka! (Oh Gentle Reader, “Fake User” is “a bit of a hack” that exists to prevent something from being discarded, in those cases where it otherwise would be. You see, every ‘thing’ has a “user count” which indicates the number of other ‘things’ which need it. When that count drops to zero, that ‘thing’ will not be saved… it will therefore go away. “Fake User” is a trick that forces this counter to be “no less than ‘1’,” thus saving our poor object from the garbage-man.)
When I selected each item and pressed FKEY, the display changed to L 0. (The item is still “linked in,” but its user-count is now zero.) When I saved the file and reloaded it, as I expected the problem was now gone. The materials were gone, so the textures that (only) they used were gone, and because all of that was gone, the library reference was gone too.
(6) Looking now at the library which I had originally linked, I notice that the “Fake User” bit was set in those materials. There was no good reason for this to be, and so I did fix the problem in the library. When I linked to the library, the “Fake User” setting was obviously carried-over as well.
And, you know, now that I understand this, I’m actually not saying that “it’s a bug.” Really, “it’s a feature.” In fact, if I was building a library (say…) strictly of “materials,” I would need for them to be “faked.” And it is plausible that I would want all of the materials in that library to remain available to me, as I (frequently… of course…) saved my work, until I consciously chose to dismiss them. That’s what the current implementation does allow me to do.
But… I sure-as-hale … :ba: … didn’t understand it at the time.
Very nice findings. Thanks for sharing 
“How soon we forget…” he muttered, annoyed to find his own post answering his current question.
Edit: No, I seem to be mistaken! In my current problem (“former DupliGroup group is still here…”), there are no fakes anywhere in the Shift+F4 hierarchy, either in the linked-from or the linked-to files.