Fix for cache-key conflict when having a \Traversable as choices
bug #9557 [DoctrineBridge] Fix for cache-key conflict when having a \Traversable as choices (DRvanR)

This PR was submitted for the 2.3-dev branch but it was merged into the 2.3 branch instead (closes #9557).

Discussion
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[DoctrineBridge] Fix for cache-key conflict when having a \Traversable as choices

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #9556
| License       | MIT
| Doc PR        | ~

Commits
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1119684 Fix for cache-key conflict when having a \Traversable as choices