bug #30500 [Mime] fixed wrong logic (fabpot)

This PR was merged into the 4.3-dev branch.

Discussion
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[Mime] fixed wrong logic

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | yes
| New feature?  | no <!-- don't forget to update src/**/CHANGELOG.md files -->
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- don't forget to update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

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Commits
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836970c776 [Mime] fixed wrong logic

src/Symfony/Component/Mime/Encoder/EightBitContentEncoder.php

@@ -20,7 +20,9 @@ final class EightBitContentEncoder implements ContentEncoderInterface
 {
     public function encodeByteStream($stream, int $maxLineLength = 0): iterable
     {
-        yield from $stream;
+        while (!feof($stream)) {
+            yield fread($stream, 16372);
+        }
     }
 
     public function getName(): string