### Please describe the problem.

Calling "git annex importfeed --relaxed" on a url of a BBC podcast
fails just like a "git annex addurl --fast" (and not relaxed) on the
url of a show:

    addurl open.live.bbc.co.uk_mediaselector_5_redir_version_2.0_mediaset_audio_nondrm_download_proto_http_vpid_p02y8kfc.mp3 
      unable to access url: http://open.live.bbc.co.uk/mediaselector/5/redir/version/2.0/mediaset/audio-nondrm-download/proto/http/vpid/p02y8kfc.mp3
    failed
    git-annex: addurl: 1 failed

I suppose that is because HEAD on that same URL returns 403 Forbidden
(addurl without fast works just fine).

"git annex addurl --relaxed" works on the given url.


### What steps will reproduce the problem?

I ran into this bug trying to importfeed various BBC podcasts. For instance:

    $ git annex importfeed --relaxed 'http://www.bbc.co.uk/programmes/p02pc9x6/episodes/downloads.rss'
    (checking known urls...)
    importfeed http://www.bbc.co.uk/programmes/p02pc9x6/episodes/downloads.rss 
    /tmp/feed3947                   100%[=======================================================>]   8,39K  --.-KB/s   en 0,007s 
    addurl Comedy_of_the_Week/In_and_Out_of_the_Kitchen__Episode_1__The_Supplement.mp3 
      unable to access url: http://open.live.bbc.co.uk/mediaselector/5/redir/version/2.0/mediaset/audio-nondrm-download/proto/http/vpid/p02yy1hn.mp3
    failed

      warning: problem downloading item
    ok


### What version of git-annex are you using? On what operating system?

git-annex version: 5.20150731-1 on a quite up-to-date debian unstable.

> Thanks for a nice test case. [[fixed|done]] --[[Joey]]
