Add PHPDbg support to HTTP components

Debug.php

@@ -45,7 +45,7 @@ class Debug
             error_reporting(-1);
         }
 
-        if ('cli' !== PHP_SAPI) {
+        if (!\in_array(PHP_SAPI, array('cli', 'phpdbg'), true)) {
             ini_set('display_errors', 0);
             ExceptionHandler::register();
         } elseif ($displayErrors && (!ini_get('log_errors') || ini_get('error_log'))) {

ErrorHandler.php

@@ -544,15 +544,16 @@ class ErrorHandler
                 }
             }
         }
+        $exceptionHandler = $this->exceptionHandler;
+        $this->exceptionHandler = null;
         try {
-            if (null !== $this->exceptionHandler) {
-                return \call_user_func($this->exceptionHandler, $exception);
+            if (null !== $exceptionHandler) {
+                return \call_user_func($exceptionHandler, $exception);
             }
             $handlerException = $handlerException ?: $exception;
         } catch (\Exception $handlerException) {
         } catch (\Throwable $handlerException) {
         }
-        $this->exceptionHandler = null;
         if ($exception === $handlerException) {
             self::$reservedMemory = null; // Disable the fatal error handler
             throw $exception; // Give back $exception to the native handler

Tests/ErrorHandlerTest.php

@@ -530,4 +530,18 @@ class ErrorHandlerTest extends TestCase
             throw $e;
         }
     }
+
+    /**
+     * @expectedException \Exception
+     * @group no-hhvm
+     */
+    public function testCustomExceptionHandler()
+    {
+        $handler = new ErrorHandler();
+        $handler->setExceptionHandler(function ($e) use ($handler) {
+            $handler->handleException($e);
+        });
+
+        $handler->handleException(new \Exception());
+    }
 }