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fix typos: remove duplicated word in comments
**What this PR does / why we need it**: Remove the duplicated word `the` in comments
**Which issue this PR fixes** : fixes #
**Special notes for your reviewer**:
```release-note
NONE
```
Although Deployment already applied its ControllerRef to adopt matching
ReplicaSets, it actually still used label selectors to list objects that
it controls. That meant it didn't actually follow the rules of
ControllerRef, so it could still fight with other controller types.
This should mean that the special handling for overlapping Deployments
is no longer necessary, since each Deployment will only see objects that
it owns (via ControllerRef).
Make rollbacks re-entrant in the Deployment controller, otherwise
fast enqueues of a Deployment may end up in undesired behavior
- redundant rollbacks.
* rolling.go (has all the logic for rolling deployments)
* recreate.go (has all the logic for recreate deployments)
* sync.go (has all the logic for getting and scaling replica sets)
* rollback.go (has all the logic for rolling back a deployment)
* util.go (contains all the utilities used throughout the controller)
Leave back at deployment_controller.go all the necessary bits for
creating, setting up, and running the controller loop.
Also add package documentation.