Snap builder fails to pull files (violation of protocol)

[Olivier - interfaSys]

I'm trying to build a snap and I get this error:

```
Preparing to pull boost
Pulling boost
EOF occurred in violation of protocol (_ssl.c:645)
Traceback (most recent call last):
  File "/usr/share/launchpad-buildd/slavebin/buildsnap", line 194, in main
    builder.pull()
  File "/usr/share/launchpad-buildd/slavebin/buildsnap", line 135, in pull
    env=env)
  File "/usr/share/launchpad-buildd/slavebin/buildsnap", line 92, in run_build_command
    self.chroot(["/bin/sh", "-c", command], echo=echo)
  File "/usr/share/launchpad-buildd/slavebin/buildsnap", line 66, in chroot
    "/usr/bin/sudo", "/usr/sbin/chroot", self.chroot_path] + args)
  File "/usr/lib/python2.7/subprocess.py", line 540, in check_call
    raise CalledProcessError(retcode, cmd)
CalledProcessError: Command '['/usr/bin/sudo', '/usr/sbin/chroot', '/home/buildd/build-SNAPBUILD-534/chroot-autobuild', 'linux32', '/bin/sh', '-c', 'cd /build/owncloud-snap && env LANG=C.UTF-8 https_proxy=https://snap-proxy.launchpad.net:3128 http_proxy=http://snap-proxy.launchpad.net:3128 SNAPCRAFT_LOCAL_SOURCES=1 snapcraft pull']' returned non-zero exit status 1
```

[Olivier - interfaSys (olivier-interfasys)]

Full build log:
https://launchpadlibrarian.net/253331237/buildlog_snap_ubuntu_xenial_armhf_owncloud-snap_BUILDING.txt.gz

[Olivier - interfaSys (olivier-interfasys)]

This is the URL that Snapcraft is trying to pull from: http://sourceforge.net/projects/boost/files/boost/1.59.0/boost_1_59_0.tar.gz

[Olivier - interfaSys (olivier-interfasys)]

I've tried with another URL and same problem, so it doesn't seem related to the hoping.
http://iweb.dl.sourceforge.net/project/boost/boost/1.59.0/boost_1_59_0.tar.gz

[Olivier - interfaSys (olivier-interfasys)]

*hopping

[Colin Watson (cjwatson)]

wget from the staging snap-proxy instance shows similar problems, ranging from a failure to establish an SSL connection after the first redirect to an HTTP hang later on. I suspect network problems on the path between us and SourceForge, but it's a little difficult to tell.

[Colin Watson (cjwatson)]

This is a somewhat wider network issue, and our sysadmins are chasing it up at the moment.

[Paul Gear (paulgear)]

We've put a fix for this in place now; please let us know if you continue to have problems.

[Colin Watson (cjwatson)]

Indeed, this seems to be fine from our staging instance now. Olivier, please try this build again.

[Olivier - interfaSys (olivier-interfasys)]

I can confirm that this is now working as expected. Thank you!