[feat] Add more testing normalizers

src/zc/buildout/testing.py

@@ -615,6 +615,10 @@ normalize_open_in_generated_script = (
 
 not_found = (re.compile(r'Not found: [^\n]+/(\w|\.)+/\r?\n'), '')
 
+could_not_retrieve = (re.compile(r"Couldn't retrieve index page for:.*\n"), '')
+
+scanning_index = (re.compile(r'Scanning index of all packages.*\n'), '')
+
 python27_warning = (re.compile(r'DEPRECATION: Python 2.7 reached the end of its '
     'life on January 1st, 2020. Please upgrade your Python as Python 2.7 is no '
     'longer maintained. A future version of pip will drop support for Python '