prevent recurrence of CID 1397192
Coverity found a possible double free in CID 1397192, which dgoulet dismissed as a False Positive. I think I found the logic by which Coverity considered a double free possible. The
done block in
test_intro_point_registration() has some calls to
tt_assert() that can jump backwards if the assertion fails, causing a double free in that unlikely event.
The block that tests
hs_circuitmap_free_all() should probably be in a helper function with its own
done label that doesn't lead to a double free if the assertion fails.
For reasons I don't understand, it looks like the renames in 6bacc3c7 caused Coverity to no longer see this potential double free, even though it looks like it changed nothing relevant.