errors on qualified buffer-names

[sboosali]

I assume this is caused by relying only on buffer-name to identify buffers. and/or not removing that hook when a buffer is renamed (by Emacs) when opening a second file with the same basename, even when neither the filename being visited nor the buffer contents have changed.

Reproduction:

(1) open README.md, enable real-auto-save-mode, autosave work.

(2) open another namesake, say ../README.md, then real-auto-save-mode still works, but errors from real-auto-save-mode-buffers with "No buffer named README.md", on both files.

(3) let's say the current directory is y/ and its parent directory is x/. then buffer-name returns the filename qualified with as much directory necessary to disambiguate it from other file buffers. i.e. README.md<x> for the former and README.md<x/y> for the latter.