you need to setgid in addition to initgroups...

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@7869 65c4cc65-6c06-0410-ace0-fbb531ad65f3

asterisk.c

@@ -2171,7 +2171,11 @@ int main(int argc, char *argv[])
 			ast_log(LOG_WARNING, "No such user '%s'!\n", runuser);
 			exit(1);
 		}
-		if (!ast_strlen_zero(rungroup)) {
+		if (!rungroup) {
+			if (setgid(pw->pw_gid)) {
+				ast_log(LOG_WARNING, "Unable to setgid to %d!\n", pw->pw_gid);
+				exit(1);
+			}
 			if (initgroups(pw->pw_name, pw->pw_gid)) {
 				ast_log(LOG_WARNING, "Unable to init groups for '%s'\n", runuser);
 				exit(1);