Linkbox have started issuing 302 redirects on some of their PUT
requests when rclone uploads a file.
This is problematic for several reasons:
1. This is the wrong redirect code - it should be 307 to preserve the method
2. Since Expect/100-Continue isn't supported the whole body gets uploaded
This fixes the problem by first doing a HEAD request on the URL. This
will allow us to read the redirect Location and not upload the body to
the wrong place.
It should still work (albeit a little more inefficiently) if Linkbox
stop redirecting the PUT requests.
See: https://forum.rclone.org/t/linkbox-upload-error/51795Fixes: #8606
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