A change in io metatable

[Sean Conner <sean@...>]

  I just noticed the following change:

commit 924bed7297d5ea16a78ec07e7acc64afad951aa8
Author: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date:   Mon Jul 1 12:25:00 2019 -0300

    Methods separated from metamethods in 'io'
    
    In the 'io' library, changed the use of the metatable also as its
    own "method table", so that metamethods cannot be accessed as if they
    were methods. (For instance, 'io.stdin.__gc' does not result in
    the finalizer metamethod anymore.)

I'm just curious as to the rational for the change.

  -spc (But you can still get to them via getmetatable())