bug #205 [UUID] Fix undefined variable in error message, and other minor fixes (guilliamxavier)
bug #205 [UUID] Fix undefined variable in error message, and other minor fixes (guilliamxavier)

This PR was squashed before being merged into the 1.13-dev branch.

Discussion
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[UUID] Fix undefined variable in error message, and other minor fixes

(all commits are actually independent)

Commits
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a7bed21 [UUID] Fix undefined variable in error message, and other minor fixes

nicolas-grekas/polyfill,symfony/polyfill