pretty: pass graph width to pretty formatting for use in '%>|(N)'

Pass graph width to pretty formatting, to make N in '%>|(N)'
include columns consumed by graph rendered when --graph option
is in use.

For example, in the output of

  git log --all --graph --pretty='format: [%>|(20)%h] %ar%d'

this change will make all commit hashes align at 20th column from
the edge of the terminal, not from the edge of the graph.

Signed-off-by: Josef Kufner <josef@kufner.cz>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/log-tree.c b/log-tree.c
index 78a5381..8d39315 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -687,6 +687,8 @@
 	ctx.output_encoding = get_log_output_encoding();
 	if (opt->from_ident.mail_begin && opt->from_ident.name_begin)
 		ctx.from_ident = &opt->from_ident;
+	if (opt->graph)
+		ctx.graph_width = graph_width(opt->graph);
 	pretty_print_commit(&ctx, commit, &msgbuf);
 
 	if (opt->add_signoff)