Reattempt download when fetch gets a 301 - during Registration

Hi,

Attached is a small patch that re-attempts a download when the first fetch
attempt during new Feed Registration gets a 301.

The use-case was when I was trying to register my blog for Planet, I got a
abc.blogspot.com feed URL whereas, in reality it was redirecting to abc.com
URL instead (because I had configured BlogSpot to do so).

So although abc.blogspot.com was working on a browser (since it redirects
on a 301) the Feed registration page failed with a 'Internal Server Error:
Attempt to download blog feed returned status 301'.

I think this is a recoverable error, and so the patch.

NB: Am (very) new to Python, so apologies for some obvious misses.

--
Robins Tharakan