When ediff-current-file compares a modified buffer with its saved
version, it creates a temporary "FILE=..." buffer to hold the saved
contents.  Currently, this buffer persists after the Ediff session
quits, requiring manual cleanup later.

In my experience, this buffer serves no further purpose once the
comparison is done, and just clutters the buffer list.  On the other
hand, I could imagine someone using it as a way to retain a snapshot of
the saved file state.

The attached patch introduces a user option that, when non-nil, causes
the "FILE=..." buffer to be killed automatically after quitting Ediff.

The default is nil, so that the patch does not modify existing behavior.

Such automatic cleanup does not seem achievable via existing Ediff
hooks.

Any feedback would be welcome.

Thanks, best,

Paul