Semicolon removed from query even when it is allowed

The Connection class removes trailing semicolons from SQL Statements, but also supports a setting to allow semicolons in statements. For some reason, SQL Server requires that a MERGE statement end in a semicolon. A good universal approach would be to change:

else {
  $this->expandArguments($query, $args);
  // To protect against SQL injection, Drupal only supports executing one
  // statement at a time.  Thus, the presence of a SQL delimiter (the
  // semicolon) is not allowed unless the option is set.  Allowing
  // semicolons should only be needed for special cases like defining a
  // function or stored procedure in SQL. Trim any trailing delimiter to
  // minimize false positives.
  $query = rtrim($query, ";  \t\n\r\0\x0B");
  if (strpos($query, ';') !== FALSE && empty($options['allow_delimiter_in_query'])) {
    throw new \InvalidArgumentException('; is not supported in SQL strings. Use only one statement at a time.');
  }
  $stmt = $this->prepareQuery($query);
  $stmt->execute($args, $options);
}

To:

else {
  $this->expandArguments($query, $args);
  // To protect against SQL injection, Drupal only supports executing one
  // statement at a time.  Thus, the presence of a SQL delimiter (the
  // semicolon) is not allowed unless the option is set.  Allowing
  // semicolons should only be needed for special cases like defining a
  // function or stored procedure in SQL. Trim any trailing delimiter to
  // minimize false positives unless delimiter is allowed.
  $whitespace = "  \t\n\r\0\x0B";
  if (empty($options['allow_delimiter_in_query'])) {
    $whitespace .= ';';
  }
  $query = rtrim($query, $whitespace);
  if (strpos($query, ';') !== FALSE && empty($options['allow_delimiter_in_query'])) {
    throw new \InvalidArgumentException('; is not supported in SQL strings. Use only one statement at a time.');
  }
  $stmt = $this->prepareQuery($query);
  $stmt->execute($args, $options);
}