log: decorate HEAD -> branch with the same color for arrow and HEAD

Commit 76c61fb (log: decorate HEAD with branch name under
--decorate=full, too - 2015-05-13) adds "HEAD -> branch" decoration to
show current branch vs detached HEAD. The sign of whether HEAD is
detached or not is "->" (vs ",") because the branch is always colored
by type. Color the arrow the same as HEAD to visually emphasize that
the following branch is HEAD, without paying too much attention to the
actual separators "->" or ","

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

log-tree.c

@@ -263,8 +263,6 @@ void format_decorations_extended(struct strbuf *sb,
 
 			if (current_and_HEAD &&
 			    decoration->type == DECORATION_REF_HEAD) {
-				strbuf_addstr(sb, color_reset);
-				strbuf_addstr(sb, color_commit);
 				strbuf_addstr(sb, " -> ");
 				strbuf_addstr(sb, color_reset);
 				strbuf_addstr(sb, decorate_get_color(use_color, current_and_HEAD->type));

t/t4207-log-decoration-colors.sh

@@ -44,7 +44,7 @@ test_expect_success setup '
 '
 
 cat >expected <<EOF
-${c_commit}COMMIT_ID${c_reset}${c_commit} (${c_reset}${c_HEAD}HEAD${c_reset}${c_commit} ->\
+${c_commit}COMMIT_ID${c_reset}${c_commit} (${c_reset}${c_HEAD}HEAD ->\
  ${c_reset}${c_branch}master${c_reset}${c_commit},\
  ${c_reset}${c_tag}tag: v1.0${c_reset}${c_commit},\
  ${c_reset}${c_tag}tag: B${c_reset}${c_commit})${c_reset} B