Do not add newlines to output

src/Composer/Util/ProcessExecutor.php

@@ -108,7 +108,7 @@ class ProcessExecutor
         if (Process::ERR === $type) {
             $this->io->writeError($buffer);
         } else {
-            $this->io->write($buffer);
+            $this->io->write($buffer, false);
         }
     }
 

tests/Composer/Test/EventDispatcher/EventDispatcherTest.php

@@ -356,7 +356,7 @@ class EventDispatcherTest extends TestCase
 
         $io->expects($this->once())
             ->method('write')
-            ->with($this->equalTo('foo'.PHP_EOL));
+            ->with($this->equalTo('foo'.PHP_EOL), false);
 
         $dispatcher->dispatchScript(ScriptEvents::POST_INSTALL_CMD, false);
     }

tests/Composer/Test/Util/ProcessExecutorTest.php

@@ -40,7 +40,7 @@ class ProcessExecutorTest extends TestCase
         $io = $this->getMock('Composer\IO\IOInterface');
         $io->expects($this->once())
             ->method('write')
-            ->with($this->equalTo('foo'.PHP_EOL));
+            ->with($this->equalTo('foo'.PHP_EOL), false);
 
         $process = new ProcessExecutor($io);
         $process->execute('echo foo');