The assumption here, that the user can run "make check insserv=/sbin/insserv" and have it run the testsuite against the installed binary is correct. This does work.
The problem encountered in the bug report is an older version of insserv is installed at /sbin/insserv. The older copy does not recognize all of the flags current used in the testsuite which is why it is failing. If a relatively newer version of insserv were installed, the testsuite would work with it. You can test this by running "make && cp insserv /tmp && make check insserv=/tmp/insserv". I think we can close this bug as the testsuite is working as expected, the locally installed version of insserv is just too old to work with the tests. - Jesse