If we've already fetched a particular URL then we do not need to do so
again within in the same operation. Maintain an internal list of fetched
URLs to avoid doing that.
(Bitbake rev: b4705c80add1f618c11a9223cdd9578d763b50ec)
Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>