When invoking the original git fetcher after downloading a mirror
tarball, BB_FETCH_PREMIRRORONLY is ignored. This leads to git fetch
commands targeting the upstream source being executed silently. Ensure
setting BB_NO_NETWORK before invoking the original fetcher. While this
was only observed for git, setting this in general for all fetcher
types makes sense at this location.
(Bitbake rev: 1b1321f2b60c0a66159e3f20c6befcb0b3ccc4c7)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>