httpconnection: correctly handle redirects from http to https
Previously the connection cache for keepalives didn't keep track of
ssl. This meant that when we connected to an https server after that
same server via http, both on the default port, we'd incorrectly reuse
the non-https connection as the default port meant the connection
cache key was the same.
$ hg init t
$ cd t
$ echo a > a
$ hg add a
$ hg commit -m test
$ rm .hg/requires
$ hg tip
abort: index 00changelog.i unknown format 2!
[255]
$ echo indoor-pool > .hg/requires
$ hg tip
abort: requirement 'indoor-pool' not supported!
[255]