The ignoreAttributes itself should be ignored, too.
merged branch derrabus/ignore_attributes_in_redirect_controller (PR #8563)

This PR was merged into the 2.3 branch.

Discussion
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[FrameworkBundle] RedirectCotroller: The ignoreAttributes parameter should be ignored

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

As discussed in PR #7590, when pointing a route to FrameworkBundle's `RedirectController` the attribute `ignoreAttributes` is added to the new route's attributes, if specified as array. As @lsmith77 wrote in a comment to that PR, this should not be the intended behavior. A valid workaround is to add `ignoreAttributes` itself to this array.

The problem remained undiscovered by the unit test, as `ignoreAttribues` was not included in the `_route_params` of the faked `Request` object. This PR should fix both, the unit test and the `RedirectController` itself, so the workaround mentioned above is not necessary anymore. Additionally, my fix should not break any routing configuration that is using the workaround.

Commits
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dc1fff0 The ignoreAttributes itself should be ignored, too.