path-walk: drop redundant parse_tree() call

path-walk: drop redundant parse_tree() call

This call to parse_tree() was flagged by Coverity for ignoring the
return value. But if we look a little further up the function, we can
see that there is already a call to parse_tree_gently(), and we'll
return early if that fails. So by this point the tree will always be
parsed, and the call is redundant.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>