Fix evaluation priority of the bootstrap settings

Closes GitLab issue #702. Thanks to Kevin Pawsey (@kevinpawsey) for
the report and the help debuging the issue.

Signed-off-by: Roberto Rosario <roberto.rosario@mayan-edms.com>

mayan/apps/smart_settings/utils.py

@@ -141,12 +141,24 @@ class BaseSetting(object):
         By default will try to get the value from the namespace symbol table,
         then the configuration file, and finally from the environment.
         """
+        # Resolution order
+        # 1 - Environment
+        # 2 - Config
+        # 3 - Global
+        # 4 - Default
         try:
-            return self.namespace.global_symbol_table.get(
-                self.name, self.namespace.get_config_file_setting(name=self.name)
-            )
-        except SettingNamespaceSingleton.SettingNotFound:
             return self.load_environment_value()
+        except SettingNamespaceSingleton.SettingNotFound:
+            try:
+                return self.namespace.get_config_file_setting(name=self.name)
+            except SettingNamespaceSingleton.SettingNotFound:
+                try:
+                    return self.namespace.global_symbol_table[self.name]
+                except KeyError:
+                    if self.has_default:
+                        return self.get_default_value()
+                    else:
+                        raise SettingNamespaceSingleton.SettingNotFound
 
     def load_environment_value(self):
         value = self._get_environment_value()
@@ -161,10 +173,7 @@ class BaseSetting(object):
                     )
                 )
         else:
-            if self.has_default:
-                return self.get_default_value()
-            else:
-                raise SettingNamespaceSingleton.SettingNotFound
+            raise SettingNamespaceSingleton.SettingNotFound
 
 
 class FilesystemBootstrapSetting(BaseSetting):
@@ -190,7 +199,13 @@ class FilesystemBootstrapSetting(BaseSetting):
         because not even the config file setup has completed.
         This setting only supports being set from the environment.
         """
-        return self.load_environment_value()
+        try:
+            return self.load_environment_value()
+        except SettingNamespaceSingleton.SettingNotFound:
+            if self.has_default:
+                return self.get_default_value()
+            else:
+                raise SettingNamespaceSingleton.SettingNotFound
 
 
 class MediaBootstrapSetting(FilesystemBootstrapSetting):