Retry tests on deadlock

Closes phpGH-12693

Author: iluuu1994

run-tests.php

@@ -2824,9 +2824,23 @@ function is_flaky(TestFile $test): bool
     return preg_match($regex, $file) === 1;
 }
 
+function is_flaky_output(string $output): bool
+{
+    $messages = [
+        '404: page not found',
+        'address already in use',
+        'connection refused',
+        'deadlock',
+        'mailbox already exists',
+        'timed out',
+    ];
+    $regex = '(\b(' . implode('|', $messages) . ')\b)i';
+    return preg_match($regex, $output) === 1;
+}
+
 function error_may_be_retried(TestFile $test, string $output): bool
 {
-    return preg_match('((timed out)|(connection refused)|(404: page not found)|(address already in use)|(mailbox already exists))i', $output) === 1
+    return is_flaky_output($output)
         || is_flaky($test);
 }