Fixed incorrect timeout in worker test

In PR #366 a timeout was unintentionally changed from LongWait to
ShortWait. This PR fixes that.

See also: https://github.com/juju/juju/pull/366#discussion_r15334468
Merge pull request #406 from mjs/worker-environ_test-wait-fix

Fixed incorrect timeout in worker test

In PR #366 a timeout in a test was unintentionally changed from LongWait to ShortWait. This PR fixes that.

See also: https://github.com/juju/juju/pull/366#discussion_r15334468