[corey.bryant,trivial] Sync charm-helpers.

Pick up jinja2 fix that enables upgrading from the quantum-gateway
charm to neutron-gateway.

hooks/charmhelpers/contrib/openstack/templating.py

@@ -29,8 +29,8 @@ from charmhelpers.contrib.openstack.utils import OPENSTACK_CODENAMES
 try:
     from jinja2 import FileSystemLoader, ChoiceLoader, Environment, exceptions
 except ImportError:
-    # python-jinja2 may not be installed yet, or we're running unittests.
-    FileSystemLoader = ChoiceLoader = Environment = exceptions = None
+    apt_install('python-jinja2', fatal=True)
+    from jinja2 import FileSystemLoader, ChoiceLoader, Environment, exceptions
 
 
 class OSConfigException(Exception):

hooks/charmhelpers/contrib/storage/linux/utils.py

@@ -67,4 +67,4 @@ def is_device_mounted(device):
     out = check_output(['mount']).decode('UTF-8')
     if is_partition:
         return bool(re.search(device + r"\b", out))
-    return bool(re.search(device + r"[0-9]+\b", out))
+    return bool(re.search(device + r"[0-9]*\b", out))

hooks/charmhelpers/core/hookenv.py

@@ -21,6 +21,7 @@
 #  Charm Helpers Developers <juju@lists.ubuntu.com>
 
 from __future__ import print_function
+import copy
 from distutils.version import LooseVersion
 from functools import wraps
 import glob
@@ -263,7 +264,7 @@ class Config(dict):
         self.path = path or self.path
         with open(self.path) as f:
             self._prev_dict = json.load(f)
-        for k, v in self._prev_dict.items():
+        for k, v in copy.deepcopy(self._prev_dict).items():
             if k not in self:
                 self[k] = v