bug#6473: describe-how-coding-system-was-decided-for-current-buffer

[jidanni]

In (info "(emacs) Recognize Coding") do mention how to make emacs say
just why it chose the coding system it did.

E.g., hide a NULL in a file,
$ { LC_ALL=zh_TW.UTF-8 date; seq 99; echo -e \\0;} >| /tmp/oo
$ emacs -Q /tmp/oo
and watch as the user goes nuts trying to figure out why emacs is not
showing the file in the usual character set anymore.

Indeed, there should be a
describe-how-coding-system-was-decided-for-current-buffer
command.