fix: only include --password in auth_args if non-empty

svn_mirror/config.py

@@ -33,9 +33,12 @@ class SVNConfig:
 
     def auth_args(self) -> list:
         """Return ``['--username', u, '--password', p]`` if configured, else []."""
-        if self.username:
-            return ["--username", self.username, "--password", self.password or ""]
+        if not self.username:
             return []
+        args = ["--username", self.username]
+        if self.password:
+            args += ["--password", self.password]
+        return args
 
     @classmethod
     def from_dict(cls, d: dict, prefix: str) -> "SVNConfig":