bug #19508 [Process] Fix AbstractPipes::write() for a situation seen …

…on HHVM (at least) (nicolas-grekas)

This PR was merged into the 2.7 branch.

Discussion
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[Process] Fix AbstractPipes::write() for a situation seen on HHVM (at least)

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | composer/composer#5381, composer/composer#5566
| License       | MIT
| Doc PR        | -

Even if I tried with my local hhvm, I can't reproduce the reported issues, yet it looks like some versions of HHVM trigger a notice here.

Commits
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2bb2b9b [Process] Fix AbstractPipes::write() for a situation seen on HHVM (at least)

src/Symfony/Component/Process/Pipes/AbstractPipes.php

@@ -134,9 +134,7 @@ protected function write()
         if (null === $this->input && !isset($this->inputBuffer[0])) {
             fclose($this->pipes[0]);
             unset($this->pipes[0]);
-        }
-
-        if (!$w) {
+        } elseif (!$w) {
             return array($this->pipes[0]);
         }
     }