Added Bulgarian translation for security component
minor #10141 [Security] added Bulgarian translation (RoumenDamianoff)

This PR was submitted for the 2.3-dev branch but it was merged into the 2.3 branch instead (closes #10141).

Discussion
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[Security] added Bulgarian translation

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

Commits
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8fceeac Added Bulgarian translation for security component
add zh_TW validator translations
minor #10144 [Validator][Translation] add zh_TW validator translations (RickySu)

This PR was merged into the 2.3 branch.

Discussion
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[Validator][Translation] add zh_TW validator translations

add Traditional Chinese validator translations.

Commits
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c755e85 add zh_TW validator translations
Added delta for Request comparison

Sometimes, tests are failing because REQUEST_TIME
changes between the creation of the various sub-requests.

By using delta, we allow maximum of second of difference.

Example: https://travis-ci.org/symfony/symfony/jobs/17668158#L511
minor #10143 [Tests] [HttpKernel] Added delta for Request comparison (lavoiesl)

This PR was submitted for the 2.3-dev branch but it was merged into the 2.3 branch instead (closes #10143).

Discussion
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[Tests] [HttpKernel] Added delta for Request comparison

| Q             | A
| ------------- | ---
| Bug fix?      | yes (in tests only)
| New feature?  | -
| BC breaks?    | -
| Deprecations? | -
| Tests pass?   | yes
| Fixed tickets | -
| License       | MIT
| Doc PR        | -

Sometimes, tests are failing because REQUEST_TIME changes between the creation of the various sub-requests.

By using delta, we allow a maximum of one second of difference.
Since this is a shady behaviour, I added minimal explanation as comments

Example: https://travis-ci.org/symfony/symfony/jobs/17668158#L511

Commits
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3a67309 [Tests] [HttpKernel] Added delta for Request comparison
[HttpFoundation] fixed typo
Revert "bug #10091 [Translation] Update PluralizationRules.php (guilhermeblanco)"

This reverts commit 61625b466d7b569abe3a0ca3c77a76a4f8467240, reversing
changes made to 35585888913a5d0459a1d3213a90ad3c0ec70e22.
Fixed data in pipe being truncated if not read before process termination