Ensure context templating doesn't fail on incomplete relation data

This is a rebuild/make sync for charms to pickup the fix in
charmhelpers to fix a change in netaddr library not allowing
falsy addresses anymore. Fix in charmhelpers is in [1].

[1] https://github.com/juju/charm-helpers/pull/921

Change-Id: I0200dcfd398757bf5cfeebac5fdda8c203045529
Signed-off-by: Guillaume Boutry <guillaume.boutry@canonical.com>

charmhelpers/contrib/network/ip.py

@@ -134,6 +134,8 @@ def get_address_in_network(network, fallback=None, fatal=False):
 
 def is_ipv6(address):
     """Determine whether provided address is IPv6 or not."""
+    if not address:
+        return False
     try:
         address = netaddr.IPAddress(address)
     except netaddr.AddrFormatError:

charmhelpers/core/host.py

@@ -357,7 +357,7 @@ def init_is_systemd(service_name=None):
     return os.path.isdir(SYSTEMD_SYSTEM)
 
 
-def adduser(username, password=None, shell='/bin/bash',
+def adduser(username, password=None, shell=None,
             system_user=False, primary_group=None,
             secondary_groups=None, uid=None, home_dir=None):
     """Add a user to the system.
@@ -389,11 +389,14 @@ def adduser(username, password=None, shell='/bin/bash',
         if home_dir:
             cmd.extend(['--home', str(home_dir)])
         if system_user or password is None:
-            cmd.append('--system')
+            cmd.extend([
+                '--system',
+                '--shell', shell if shell else '/usr/sbin/nologin'
+            ])
         else:
             cmd.extend([
                 '--create-home',
-                '--shell', shell,
+                '--shell', shell if shell else '/bin/bash',
                 '--password', password,
             ])
         if not primary_group:

charmhelpers/fetch/ubuntu.py

@@ -341,7 +341,7 @@ UBUNTU_OPENSTACK_RELEASE = OrderedDict([
 ])
 
 
-APT_NO_LOCK = 100  # The return code for "couldn't acquire lock" in APT.
+APT_ERROR_CODE = 100  # The return code for APT errors.
 CMD_RETRY_DELAY = 10  # Wait 10 seconds between command retries.
 CMD_RETRY_COUNT = 10  # Retry a failing fatal command X times.
 
@@ -464,6 +464,8 @@ def apt_upgrade(options=None, fatal=False, dist=False):
 def apt_update(fatal=False):
     """Update local apt cache."""
     cmd = ['apt-get', 'update']
+    if fatal:
+        cmd.append("--error-on=any")
     _run_apt_command(cmd, fatal)
 
 
@@ -1021,8 +1023,7 @@ def _run_apt_command(cmd, fatal=False, quiet=False):
     """
     if fatal:
         _run_with_retries(
-            cmd, retry_exitcodes=(1, APT_NO_LOCK,),
-            retry_message="Couldn't acquire DPKG lock",
+            cmd, retry_exitcodes=(1, APT_ERROR_CODE,),
             quiet=quiet)
     else:
         kwargs = {}