RequestInterceptor not applied when query executed as stream

[redfaithful]

I tried to use BasicAuthenticationExtension when applying the query as stream, and the header is not added to the query.

In BasicAuthenticationSpec, queries are tested to include the header only with the .execute method and not with .streamAs method. Attached a patch with a scenario testing this issue and failing.
Test_basic_authentication_with_streaming.txt

[redfaithful]

Adding a fix to this issue, including the modified test.
Fix_basic_authentication_with_streaming.txt