git am with MIME

There's still a problem with git am on the current next branch (which
includes the recent "mailinfo: re-fix MIME multipart boundary parsing"
patch):

$ wcat -q
'http://article.gmane.org/gmane.comp.version-control.git/91305/raw' | git am
fatal: `pos + len' is too far after the end of the buffer
$

It seems to be because of the (unusual?) way the patch uses MIME.  Just
wanted to post this so it doesn't get lost.

-- Lea