Work around IIS bug for redirects FS#1576

Ignore-this: 37b33f575e4c0b31e4af93185bf74f0f

When IIS is running PHP in CGI mode it will not send cookie headers on 302
redirections. This is a known bug (KB176113).

This patch will detect affected servers. Instead of a 302 redirect a Refresh:
header is issued. This is supported by all known browsers should have the same
effect as a real redirect.

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