git name-rev not accepting abbreviated SHA with --stdin

[Sitaram Chamarty <sitaramc@gmail.com>]

Hi all,

"git name-rev" does not accept abbreviated SHAs if --stdin is used,
though it works when the SHA is given directly on the command line:

    $ git version
    git version 2.4.3
    $ git name-rev --tags d73f544
    d73f544 tags/v3.6.3~29
    $ git name-rev --tags --stdin <<< d73f544
    d73f544

This *is* documented, but I'm curious why this distinction is made.  Is
it merely a matter of parsing or were there some other complications I
am unaware of, which forced this distinction to be made?

thanks
sitaram