Fix Host header on stream commands

Fixes #8407

Setting Host on URL only works if the Request does not
already have its Host property set.

Note that the API version was also swallowed.

Signed-off-by: Tõnis Tiigi <tonistiigi@gmail.com> (github: tonistiigi)
Merge pull request #8408 from tonistiigi/8407-fix-host-header

Fix Host header on stream commands