The golang.org/x/sync package was vendored using the
github.com/golang/sync URL, but this is not the canonical
URL.
Because of this, vendoring failed in Moby, as it detects
these to be a duplicate import:
vndr github.com/golang/sync
2018/03/14 11:54:37 Collecting initial packages
2018/03/14 11:55:00 Download dependencies
2018/03/14 11:55:00 Failed to parse config: invalid config format: // FIXME this should be golang.org/x/sync, which is already vendored above
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>