* bzrlib/ui/__init__.py: (CLIUIFactory.prompt): Display prompt on stderr.
* bzrlib/tests/test_ui.py: (UITests.test_text_factory_ascii_password, UITests.test_text_factory_utf8_password, UITests.assert_get_bool_acceptance_of_user_input, UITests.test_text_factory_prompt, UITests.test_silent_ui_getusername, UITests.test_text_ui_getusername, UITests.test_text_ui_getusername_utf8):prompt is now displayed on stderr.
* bzrlib/tests/test_http.py: (TestAuth.test_prompt_for_username, TestAuth.test_prompt_for_password): prompt is now displayed on stderr.
* bzrlib/tests/test_config.py: (TestAuthenticationConfig._check_default_password_prompt, TestAuthenticationConfig._check_default_username_prompt): prompt is now displayed on stderr.