Ensure get_requests_for_local_unit doesn't fail on incomplete relation

This is a rebuild/make sync for charms to pickup the fix in charmhelpers to fix
any inadvertant accesses of ['ca'] in the relation data before it is available
from vault in the certificates relation.  Fix in charmhelpers is in [1].

[1] juju/charm-helpers#824
Closes-Bug: #2028683

Change-Id: I380e012bee8c415aaf1929d06d64552319d6356b

rebuild

@@ -2,4 +2,4 @@
 # when dependencies of the charm change,
 # but nothing in the charm needs to.
 # simply change the uuid to something new
-53b9d6fe-1178-11ec-b441-e3334d9920e6
+080c115c-31fd-11ee-81bb-33d8b4248c07