Comment 3 for bug 1533227

Still reproducing.

 with:
  ISO: fuel-community-8.0-1395-2016-01-15_07-18-51.iso
  patch to fuel-agent: patch set7 of https://review.openstack.org/266771
  patch to fuel-library: patch set1 of https://review.openstack.org/268094

Steps to reproduce:
1. Setup proxy server on host (192.168.0.30:3128 for me)
2. Create VM with two interfaces, host-only and internal network
3. Boot VM from ISO (fuel-community-8.0-1395-2016-01-15_07-18-51.iso)
4. Add host 192.168.0.30:3128 as proxy in fuel-bootstrap
5. Save and quit -> fails same as original report
6. cd /usr/lib/python2.7/site-packages; patch -p1 < /tmp/patch-from-266771
7. cd /etc/puppet/modules/nailgun/examples/; patch -p5 < /tmp/patch-from-268094
8. fuel-bootstrap -v build --activate` 2>&1 |tee fuel-bootstrap.log

Expected behavior:
Ubuntu bootstrap is built and activates

Actual behavior:
Ubuntu bootstrap is failed to build

Detailed output:

Full output `fuel-bootstrap.log` is here http://paste.openstack.org/show/484077/

----------- a snip from the log --------------------
Adding repository preference: name=mos, priority=1050
Trying to initialize http request object http://127.0.0.1:8080/ubuntu/x86_64/dists/mos8.0/Release, byte range: 0
Starting new HTTP connection (1): 192.168.0.30
"GET http://127.0.0.1:8080/ubuntu/x86_64/dists/mos8.0/Release HTTP/1.1" 503 3435
Successful http request to http://127.0.0.1:8080/ubuntu/x86_64/dists/mos8.0/Release on 1 retry
Failed to build bootstrap image: 503 Server Error: Service Unavailable
Cleanup chroot
Trying to execute command: fuser -v /tmp/tmpU8hWb_.fuel-agent-image
There are no running processes in /tmp/tmpU8hWb_.fuel-agent-image
Finally: umounting procfs /tmp/tmpU8hWb_.fuel-agent-image/proc
Trying to execute command: mountpoint -q /tmp/tmpU8hWb_.fuel-agent-image/proc
Trying to umount /tmp/tmpU8hWb_.fuel-agent-image/proc
Trying to execute command: umount /tmp/tmpU8hWb_.fuel-agent-image/proc
Finally: umounting chroot tree /tmp/tmpU8hWb_.fuel-agent-image
Umounting target file systems: /tmp/tmpU8hWb_.fuel-agent-image
Trying to execute command: mountpoint -q /tmp/tmpU8hWb_.fuel-agent-image/
Trying to umount /tmp/tmpU8hWb_.fuel-agent-image/
Trying to execute command: umount /tmp/tmpU8hWb_.fuel-agent-image/
Finally: detaching loop device: /dev/loop1
Trying to figure out if loop device /dev/loop1 is attached
Trying to execute command: losetup -a
Loop device /dev/loop1 seems to be attached. Trying to detach.
Trying to execute command: losetup -d /dev/loop1
Finally: removing temporary file: /tmp/tmpzrZCoC.fuel-agent-image
503 Server Error: Service Unavailable
clean up BuildCommand
got an error: 503 Server Error: Service Unavailable
----------- a snip from the log --------------------

http proxy server log (squid on 192.168.0.30) :
[18/Jan/2016:00:38:29 +0900.783] 1 192.168.0.100 TCP_MISS/503 3769 GET http
://127.0.0.1:8080/ubuntu/x86_64/dists/mos8.0/Release - HIER_DIRECT/127.0.0.1 tex
t/html

It should not come to here!