the method nailgun.statistics.utils.set_proxy swallows exception from client code

[Bulat Gaifullin]

run the following code:
with nailgun.statistics.utils.set_proxy("test proxy"):
     raise RuntimeError("some error")

some block of code

expected result:
  some block of code will not run

actual result:
  the exception will swallows in nailgun.statistics.utils.set_proxy and some block of code will run

this behaviour is not expected for this method and may cause new bugs in future.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/220562

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/220562
Committed: https://git.openstack.org/cgit/stackforge/fuel-web/commit/?id=730e682db79da7be6a41a090ba7f7e41d9577008
Submitter: Jenkins
Branch: master

commit 730e682db79da7be6a41a090ba7f7e41d9577008
Author: Bulat Gaifullin <email address hidden>
Date: Fri Sep 4 18:39:15 2015 +0300

    set_proxy swallows exceptions fixed

    1. move error handling to the client code. statistics.oswl.collector
    2. update tests according to new behaviour
    3. remove double lookup in environment variables upon init proxy context

    Change-Id: I565ad63811bec85f6a0436050927f39a4802820b
    Closes-Bug: #1491856

[Nastya Urlapova (aurlapova)]

nailgun/test/unit/fuel_statistics_tests/test_utils_functions.py::TestUtilsFunctions::test_set_proxy_func
[gw1] PASSED nailgun/test/unit/fuel_statistics_tests/test_utils_functions.py::TestUtilsFunctions::test_set_proxy_func

https://ci.fuel-infra.org/job/gate-fuel-web/1355/consoleFull