tox: bump the pylint version to 2.6.0 in the default run (#544)

Changes:

tox: bump the pylint version to 2.6.0 in the default run
Fix pylint 2.6.0 W0707 warnings (raise-missing-from)

4 files changed, 20 insertions, 14 deletions

diff --git a/cloudinit/net/__init__.py b/cloudinit/net/__init__.py
index 322af77b..e233149a 100644
--- a/cloudinit/net/__init__.py
+++ b/cloudinit/net/__init__.py
@@ -506,7 +506,9 @@ def apply_network_config_names(netcfg, strict_present=True, strict_busy=True):
     try:
         _rename_interfaces(extract_physdevs(netcfg))
     except RuntimeError as e:
-        raise RuntimeError('Failed to apply network config names: %s' % e)
+        raise RuntimeError(
+            'Failed to apply network config names: %s' % e
+        ) from e
 
 
 def interface_has_own_mac(ifname, strict=False):
@@ -965,7 +967,8 @@ class EphemeralIPv4Network(object):
             self.prefix = mask_to_net_prefix(prefix_or_mask)
         except ValueError as e:
             raise ValueError(
-                'Cannot setup network: {0}'.format(e))
+                'Cannot setup network: {0}'.format(e)
+            ) from e
 
         self.connectivity_url = connectivity_url
         self.interface = interface
diff --git a/cloudinit/net/cmdline.py b/cloudinit/net/cmdline.py
index 7ca7262b..cc8dc17b 100755
--- a/cloudinit/net/cmdline.py
+++ b/cloudinit/net/cmdline.py
@@ -112,8 +112,8 @@ def _klibc_to_config_entry(content, mac_addrs=None):
     data = util.load_shell_content(content)
     try:
         name = data['DEVICE'] if 'DEVICE' in data else data['DEVICE6']
-    except KeyError:
-        raise ValueError("no 'DEVICE' or 'DEVICE6' entry in data")
+    except KeyError as e:
+        raise ValueError("no 'DEVICE' or 'DEVICE6' entry in data") from e
 
     # ipconfig on precise does not write PROTO
     # IPv6 config gives us IPV6PROTO, not PROTO.
diff --git a/cloudinit/net/dhcp.py b/cloudinit/net/dhcp.py
index 9230cf7a..4394c68b 100644
--- a/cloudinit/net/dhcp.py
+++ b/cloudinit/net/dhcp.py
@@ -82,8 +82,8 @@ class EphemeralDHCPv4(object):
         try:
             leases = maybe_perform_dhcp_discovery(
                 self.iface, self.dhcp_log_func)
-        except InvalidDHCPLeaseFileError:
-            raise NoDHCPLeaseError()
+        except InvalidDHCPLeaseFileError as e:
+            raise NoDHCPLeaseError() from e
         if not leases:
             raise NoDHCPLeaseError()
         self.lease = leases[-1]
diff --git a/cloudinit/net/network_state.py b/cloudinit/net/network_state.py
index 7bfe8be0..b2f7d31e 100644
--- a/cloudinit/net/network_state.py
+++ b/cloudinit/net/network_state.py
@@ -297,9 +297,10 @@ class NetworkStateInterpreter(metaclass=CommandHandlerMeta):
             command_type = command['type']
             try:
                 handler = self.command_handlers[command_type]
-            except KeyError:
-                raise RuntimeError("No handler found for"
-                                   " command '%s'" % command_type)
+            except KeyError as e:
+                raise RuntimeError(
+                    "No handler found for  command '%s'" % command_type
+                ) from e
             try:
                 handler(self, command)
             except InvalidCommand:
@@ -316,9 +317,10 @@ class NetworkStateInterpreter(metaclass=CommandHandlerMeta):
                 continue
             try:
                 handler = self.command_handlers[command_type]
-            except KeyError:
-                raise RuntimeError("No handler found for"
-                                   " command '%s'" % command_type)
+            except KeyError as e:
+                raise RuntimeError(
+                    "No handler found for command '%s'" % command_type
+                ) from e
             try:
                 handler(self, command)
                 self._v2_common(command)
@@ -914,9 +916,10 @@ def _normalize_route(route):
     if metric:
         try:
             normal_route['metric'] = int(metric)
-        except ValueError:
+        except ValueError as e:
             raise TypeError(
-                'Route config metric {} is not an integer'.format(metric))
+                'Route config metric {} is not an integer'.format(metric)
+            ) from e
     return normal_route