py: Don't expose 0.0.0.0 as destination IP for tests (#14324)

Webkit recently[1] started blocking 0.0.0.0 as destination addresses,
and Chrome is also in the process of enabling such change[2].

This commit falls back to use the default localhost IP instead of 0.0.0.0
if we don't want to use the real IP. And if the server is actually using
0.0.0.0, fallback to localhost when generating the URL for the tests.

[1] WebKit/WebKit@e59cd4a
[2] https://chromestatus.com/feature/5106143060033536

Co-authored-by: Diego Molina <diemol@users.noreply.github.com>

py/conftest.py

@@ -320,7 +320,7 @@ def wait_for_server(url, timeout):
 
 @pytest.fixture(autouse=True, scope="session")
 def webserver(request):
-    host = get_lan_ip() if request.config.getoption("use_lan_ip") else "0.0.0.0"
+    host = get_lan_ip() if request.config.getoption("use_lan_ip") else None
 
     webserver = SimpleWebServer(host=host)
     webserver.start()

py/test/selenium/webdriver/common/webserver.py

@@ -138,7 +138,7 @@ class SimpleWebServer:
 
     def __init__(self, host=DEFAULT_HOST_IP, port=DEFAULT_PORT):
         self.stop_serving = False
-        host = host
+        host = host if host else DEFAULT_HOST_IP
         port = port
         while True:
             try:
@@ -171,7 +171,8 @@ def stop(self):
 
     def where_is(self, path, localhost=False) -> str:
         # True force serve the page from localhost
-        if localhost:
+        # 0.0.0.0 shouldn't be used as a destination address, so fallback to localhost
+        if localhost or self.host == "0.0.0.0":
             return f"http://{DEFAULT_HOST}:{self.port}/{path}"
         return f"http://{self.host}:{self.port}/{path}"