[dbmanager] Use user name as DB name if provided

Followup for 212b125

Author: Alessandro Pasotti

python/plugins/db_manager/db_plugins/postgis/connector.py

@@ -53,10 +53,10 @@ def __init__(self, uri):
 
         # Do not get db and user names from the env if service is used
         if uri.service() is None:
-            self.dbname = uri.database() or os.environ.get('PGDATABASE') or username
-            uri.setDatabase(self.dbname)
             if username is None:
                 username = os.environ.get('USER')
+            self.dbname = uri.database() or os.environ.get('PGDATABASE') or username
+            uri.setDatabase(self.dbname)
 
         expandedConnInfo = self._connectionInfo()
         try: