Usability improvement request: git show revision -- file

Hi,

if there's existing way to do this please tell me.

There's this file "src/subdir/file". I'm in the "src" directory and want to see the "file" at specific revision.

Knowing about git show I'd expect something like this to work:

   $ git show master -- subdir/file

But it shows nothing (no output, no warning). Following also does not work as expected:

   $ git show master:subdir/file
   fatal: Path 'src/subdir/file' exists, but not 'subdir/file'.
   Did you mean 'master:src/subdir/file'?

Of course following works:

   $ git show master:src/subdir/file

but it's not very convenient to have to specify full path, and it's not what you would expect given that most other commands accept "-- relativepath" syntax.