Close #19494: add urrlib.request.HTTPBasicPriorAuthHandler

This auth handler adds the Authorization header to the first
HTTP request rather than waiting for a HTTP 401 Unauthorized
response from the server as the default HTTPBasicAuthHandler
does.

This allows working with websites like https://api.github.com which do
not follow the strict interpretation of RFC, but more the dicta in the
end of section 2 of RFC 2617:

    > A client MAY preemptively send the corresponding Authorization
    > header with requests for resources in that space without receipt
    > of another challenge from the server.  Similarly, when a client
    > sends a request to a proxy, it may reuse a userid and password in
    > the Proxy-Authorization header field without receiving another
    > challenge from the proxy server. See section 4 for security
    > considerations associated with Basic authentication.

Patch by Matej Cepl.

1 files changed, 3 insertions, 0 deletions

diff --git a/Misc/NEWS b/Misc/NEWS
index 431015a..1c72d96 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -183,6 +183,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #19494: Added urllib.request.HTTPBasicPriorAuthHandler. Patch by
+  Matej Cepl.
+
 - Issue #22578: Added attributes to the re.error class.
 
 - Issue #12728: Different Unicode characters having the same uppercase but