When downloadfilename is defined in a recipe's SRC_URI and PREMIRRORS is also
defined using the same URI, the downloadfilename is appended to the mirror
URI and it should not be.
[YOCTO #13039]
(Bitbake rev: 8a3ff9f3eaf19d4258eb070c5dc230dface269b2)
Signed-off-by: Scott Weaver <weaverjs@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>