bpo-35121: prefix dot in domain for proper subdomain validation (GH-10258) (GH-12261)

Don't send cookies of domain A without Domain attribute to domain B when domain A is a suffix match of domain B while using a cookiejar with `http.cookiejar.DefaultCookiePolicy` policy.  Patch by Karthikeyan Singaravelan.
(cherry picked from commit ca7fe5063593958e5efdf90f068582837f07bd14)

Co-authored-by: Xtreak <tir.karthi@gmail.com>
3 files changed