strpos($location, "/") === 0 is not a valid way to detect absolute …

…paths on Windows: it fails on `D:/a/cli/cli/config/…`.

src/Command/App/NewFromDrupal7Command.php

@@ -95,14 +95,22 @@ private function getLocation(string $location, bool $should_exist = TRUE): strin
       elseif (!$file_exists && $should_exist) {
         throw new ValidatorException(sprintf('%s could not be located. Check that the path is correct and try again.', $location));
       }
-      if (strpos($location, '.') === 0 || strpos($location, '/') !== 0) {
+      if (strpos($location, '.') === 0 || !static::isAbsolutePath($location)) {
         $absolute = getcwd() . '/' . $location;
         $location = $should_exist ? realpath($absolute) : $absolute;
       }
     }
     return $location;
   }
 
+  private static function isAbsolutePath(string $path): bool {
+    if ($path === '') {
+      throw new \InvalidArgumentException();
+    }
+    // @see https://stackoverflow.com/a/23570509
+    return $path[0] === DIRECTORY_SEPARATOR || preg_match('~\A[A-Z]:(?![^/\\\\])~i', $path) > 0;
+  }
+
   protected function execute(InputInterface $input, OutputInterface $output): int {
     try {
       $inspector = $this->getInspector($input);