systemd-systemctl: fix errors in instance name expansion

If the instance name indicated by %i begins with a number, the meaning of the
replacement string "\\1{}".format(instance) is ambiguous.

To indicate group number 1 regardless of the instance name, use "\g<1>".

(From OE-Core rev: d18b939fb08b37380ce95934da38e6522392621c)

(From OE-Core rev: 682e094e6af67e67873f7f08dd8d52b40fcdbded)

Signed-off-by: Yuta Hayama <hayama@lineo.co.jp>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

meta/recipes-core/systemd/systemd-systemctl/systemctl

@@ -189,7 +189,7 @@ class SystemdUnit():
         try:
             for dependent in config.get('Install', prop):
                 # expand any %i to instance (ignoring escape sequence %%)
-                dependent = re.sub("([^%](%%)*)%i", "\\1{}".format(instance), dependent)
+                dependent = re.sub("([^%](%%)*)%i", "\\g<1>{}".format(instance), dependent)
                 wants = systemdir / "{}.{}".format(dependent, dirstem) / service
                 add_link(wants, target)