Predicate hasHostnameSanitizingSubstring

Holds if the string value of nd prevents anything appended after it from affecting the hostname of a URL.

Specifically, this holds if the string contains any of the following:

• ? (any suffix becomes part of query)
• # (any suffix becomes part of fragment)
• / or \, immediately prefixed by a character other than :, /, or \ (any suffix becomes part of the path)
• a leading / or \ followed by a character other than / or \ (any suffix becomes part of the path)

In the latter two cases, the additional check is necessary to avoid a / that could be interpreted as the // separating the (optional) scheme from the hostname.