[ovs-git] [openvswitch/ovs] aaa1cf: travis: Retry kernel download on 503 first byte ti...

[Ilya Maximets]

  Branch: refs/heads/master
  Home:   https://github.com/openvswitch/ovs
  Commit: aaa1cf41f0ec1a6a3e82d23f9bdbeae411389c98
      https://github.com/openvswitch/ovs/commit/aaa1cf41f0ec1a6a3e82d23f9bdbeae411389c98
  Author: Ilya Maximets <i.maximets at samsung.com>
  Date:   2019-05-20 (Mon, 20 May 2019)

  Changed paths:
    M .travis/linux-build.sh

  Log Message:
  -----------
  travis: Retry kernel download on 503 first byte timeout.

Sometimes it takes to long for CDN to reply in case of downloading
of not frequently used kernels.
For example, even on my local PC it fails to download linux-4.19.29
at the first try:

  $ wget https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.19.29.tar.xz
  Resolving cdn.kernel.org (cdn.kernel.org)... 151.101.1.176
  Connecting to cdn.kernel.org |151.101.1.176|:443... connected.
  HTTP request sent, awaiting response... 503 first byte timeout

Example from TravisCI:
  https://travis-ci.org/openvswitch/ovs/jobs/530247589

It seems that CDN downloads the tar for that time to the nearby
server and instant retry usually succeeds immediately.

503 is not a "fatal error" for wget and, unfortunately, wget on
TravisCI is too old and we can't just use "--retry-on-http-error=503"
to avoid failures in this case. So, let's just retry unconditionally.
Fallback to the direct download if CDN fails twice.

Fixes: ae6e4f12fcab ("travis: Speed up linux kernel downloads.")
Signed-off-by: Ilya Maximets <i.maximets at samsung.com>
Signed-off-by: Ben Pfaff <blp at ovn.org>