revert-buffer and changes in encoding

[Richard Stallman]

We have had discussions in the past about how revert-buffer
should deal with encoding.  I think this statement, by Stefan,
is the right thing to do:

    Looks like we should remember whether the current coding-system was
    automatically inferred or whether it was explicitly specified.
    Of course, we need to remember it separatly for the line-ending part
    of the coding-system.

If the file was originally visited with a specified coding system,
revert-buffer should keep on using that specified coding system.  If
the file coding system was autodetected before, revert-buffer should
autodetect it again, and it should set buffer-file-coding-system again
so that saving the buffer uses the most recent coding system.

Setting this flag to record whether the coding system was explicitly
specified is easy to do in Finsert_buffer.  It should only set this
flag when the VISIT argument specifies visiting a file.

Can someone please implement this, and ack to me?