TestInstallMongodServiceExists fails on centos

[Martin Packman]

TestInstallMongodServiceExists is failing on the precise unit test runs in CI.

<http://reports.vapour.ws/releases/issue/55e6f77f749a5640afd59e02>

FAIL: mongo_test.go:499: MongoSuite.TestInstallMongodServiceExists
...
mongo_test.go:532:
    testing.AssertEchoArgs(c, "apt-get", expectedJujuMongodb...)
/home/ubuntu/juju-core_1.26-alpha1/src/github.com/juju/testing/cmd.go:194:
    c.Assert(actual, gc.Equals, expected)
... obtained string = "apt-get '--option=Dpkg::Options::=--force-confold' '--option=Dpkg::options::=--force-unsafe-io' '--assume-yes' '--quiet' 'install' '--target-release' 'precise-updates/cloud-tools' 'mongodb-server'"
... expected string = "apt-get '--option=Dpkg::Options::=--force-confold' '--option=Dpkg::options::=--force-unsafe-io' '--assume-yes' '--quiet' 'install' 'juju-mongodb'"

Seems to be due to test change from pr #3170:

<https://github.com/juju/juju/commit/cbd011823ef2b9645fde7824054109d3c5c2ae84>

[Curtis Hovey (sinzui)]

This appears to be fixed in precise, but still present in centos (for other reasons).

[Bogdan Teleaga (bteleaga)]

http://data.vapour.ws/juju-ci/products/version-3545/run-unit-tests-centos7-amd64/build-426/consoleText

This seems to pass on CentOS, am I missing something?