name-rev: use 'name->tip_name' instead of 'tip_name'

Following the previous patches in this series we can get the value of
'name_rev()'s 'tip_name' parameter from the 'struct rev_name'
associated with the commit as well.

So let's use 'name->tip_name' instead, which makes the patch
eliminating the recursion of name_rev() a bit easier to follow.

Note that at this point we could drop the 'tip_name' parameter as
well, but that parameter will be necessary later, after the recursion
is eliminated.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/name-rev.c

diff --git a/builtin/name-rev.c b/builtin/name-rev.c
index fc61d6f..6c1e6e9 100644
--- a/builtin/name-rev.c
+++ b/builtin/name-rev.c
@@ -126,18 +126,21 @@ static void name_rev(struct commit *commit,
 		if (parent_number > 1) {
 			size_t len;
 
-			strip_suffix(tip_name, "^0", &len);
+			strip_suffix(name->tip_name, "^0", &len);
 			if (name->generation > 0)
-				new_name = xstrfmt("%.*s~%d^%d", (int)len, tip_name,
+				new_name = xstrfmt("%.*s~%d^%d",
+						   (int)len,
+						   name->tip_name,
 						   name->generation,
 						   parent_number);
 			else
-				new_name = xstrfmt("%.*s^%d", (int)len, tip_name,
+				new_name = xstrfmt("%.*s^%d", (int)len,
+						   name->tip_name,
 						   parent_number);
 			generation = 0;
 			distance = name->distance + MERGE_TRAVERSAL_WEIGHT;
 		} else {
-			new_name = tip_name;
+			new_name = name->tip_name;
 			generation = name->generation + 1;
 			distance = name->distance + 1;
 		}