[FrameworkBundle] Allowed "0" as a checkbox value in the php template.
bug #9711 [FrameworkBundle] Allowed "0" as a checkbox value in php templates (jakzal)

This PR was merged into the 2.3 branch.

Discussion
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[FrameworkBundle] Allowed "0" as a checkbox value in php templates

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #8251
| License       | MIT
| Doc PR        |

Commits
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955e8cf [FrameworkBundle] Allowed "0" as a checkbox value in the php template.