fixup: make requested changes

- Use `config.basename` instead of re-parsing config path
- Update docstring (final """)

sopel/db.py

@@ -89,7 +89,8 @@ class SopelDB(object):
     to the database, wherever the user has configured it to be.
 
     When configured with a relative filename, it is assumed to be in the directory
-    set (or defaulted to) in the core setting 'homedir'."""
+    set (or defaulted to) in the core setting 'homedir'.
+    """
 
     def __init__(self, config):
         # MySQL - mysql://username:password@localhost/db
@@ -99,10 +100,8 @@ def __init__(self, config):
         # Handle SQLite explicitly as a default
         if db_type == 'sqlite':
             path = config.core.db_filename
-            _, config_file = os.path.split(config.filename)
-            config_name, _ = os.path.splitext(config_file)
             if path is None:
-                path = os.path.join(config.core.homedir, config_name + '.db')
+                path = os.path.join(config.core.homedir, config.basename + '.db')
             path = os.path.expanduser(path)
             if not os.path.isabs(path):
                 path = os.path.normpath(os.path.join(config.core.homedir, path))