Confirmed this issue remains in charm-manila master:

2017-11-22 10:05:34 DEBUG install Preparing to unpack .../python3-psutil_3.4.2-1_amd64.deb ...
2017-11-22 10:05:34 DEBUG install Unpacking python3-psutil (3.4.2-1) ...
2017-11-22 10:05:35 DEBUG install Setting up python3-psutil (3.4.2-1) ...
2017-11-22 10:05:37 DEBUG install Traceback (most recent call last):
2017-11-22 10:05:37 DEBUG install   File "/var/lib/juju/agents/unit-manila-0/charm/hooks/install", line 19, in <module>
2017-11-22 10:05:37 DEBUG install     main()
2017-11-22 10:05:37 DEBUG install   File "/var/lib/juju/agents/unit-manila-0/.venv/lib/python3.5/site-packages/charms/reactive/__init__.py", line 110, in main
2017-11-22 10:05:37 DEBUG install     bus.discover()
2017-11-22 10:05:37 DEBUG install   File "/var/lib/juju/agents/unit-manila-0/.venv/lib/python3.5/site-packages/charms/reactive/bus.py", line 398, in discover
2017-11-22 10:05:37 DEBUG install     _register_handlers_from_file(search_path, filepath)
2017-11-22 10:05:37 DEBUG install   File "/var/lib/juju/agents/unit-manila-0/.venv/lib/python3.5/site-packages/charms/reactive/bus.py", line 428, in _register_handlers_from_file
2017-11-22 10:05:37 DEBUG install     _load_module(root, filepath)
2017-11-22 10:05:37 DEBUG install   File "/var/lib/juju/agents/unit-manila-0/.venv/lib/python3.5/site-packages/charms/reactive/bus.py", line 416, in _load_module
2017-11-22 10:05:37 DEBUG install     return importlib.import_module(package + module)
2017-11-22 10:05:37 DEBUG install   File "/var/lib/juju/agents/unit-manila-0/.venv/lib/python3.5/importlib/__init__.py", line 126, in import_module
2017-11-22 10:05:37 DEBUG install     return _bootstrap._gcd_import(name[level:], package, level)
2017-11-22 10:05:37 DEBUG install   File "<frozen importlib._bootstrap>", line 986, in _gcd_import
2017-11-22 10:05:37 DEBUG install   File "<frozen importlib._bootstrap>", line 969, in _find_and_load
2017-11-22 10:05:37 DEBUG install   File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
2017-11-22 10:05:37 DEBUG install   File "<frozen importlib._bootstrap>", line 673, in _load_unlocked
2017-11-22 10:05:37 DEBUG install   File "<frozen importlib._bootstrap_external>", line 665, in exec_module
2017-11-22 10:05:37 DEBUG install   File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed
2017-11-22 10:05:37 DEBUG install   File "/var/lib/juju/agents/unit-manila-0/charm/hooks/relations/manila-plugin/provides.py", line 20, in <module>
2017-11-22 10:05:37 DEBUG install     class ManilaPluginProvides(reactive.RelationBase):
2017-11-22 10:05:37 DEBUG install   File "/var/lib/juju/agents/unit-manila-0/charm/hooks/relations/manila-plugin/provides.py", line 39, in ManilaPluginProvides
2017-11-22 10:05:37 DEBUG install     class states(reactive.bus.StateList):
2017-11-22 10:05:37 DEBUG install   File "/var/lib/juju/agents/unit-manila-0/charm/hooks/relations/manila-plugin/provides.py", line 40, in states
2017-11-22 10:05:37 DEBUG install     connected = reactive.bus.State('{relation_name}.connected')
2017-11-22 10:05:37 DEBUG install AttributeError: module 'charms.reactive.bus' has no attribute 'State'
2017-11-22 10:05:37 ERROR juju.worker.uniter.operation runhook.go:107 hook "install" failed: exit status 1