This commit is necessary to introduce proxy fetchers and do not modify
the behavior of existing fetchers.
This commit allows fetchers to forwards the "try_mirrors" functions to
a proxy fetcher.
(Bitbake rev: 462c9a2b368a1720da276310b1d5d0423b7cefea)
Signed-off-by: Jean-Marie LEMETAYER <jean-marie.lemetayer@savoirfairelinux.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>