Merge branch 'jc/diff-tree-stdin-fix' into maint

"diff-tree --stdin" has been broken for about a year, but 2.36
release broke it even worse by breaking running the command with
<pathspec>, which in turn broke "gitk" and got noticed.  This has
been corrected by aligning its behaviour to that of "log".

This fixes a regression in 2.36 and is slate to go to 2.36.1
source: <xmqq7d7bsu2n.fsf@gitster.g>

* jc/diff-tree-stdin-fix:
  2.36 gitk/diff-tree --stdin regression fix

log-tree.c

@@ -1098,6 +1098,7 @@ int log_tree_commit(struct rev_info *opt, struct commit *commit)
 	opt->loginfo = &log;
 	opt->diffopt.no_free = 1;
 
+	/* NEEDSWORK: no restoring of no_free?  Why? */
 	if (opt->line_level_traverse)
 		return line_log_print(opt, commit);