Ensure file URIs without a host build with slashes

[matt-allan]

If you parse a file uri without a host like file:///etc/hosts, it will rebuild as file:/etc/hosts. This PR fixes Uri\build to add the missing // for file URIs that don't have a host.

The docs for parse_url say:

This function is intended specifically for the purpose of parsing URLs and not URIs. However, to comply with PHP's backwards compatibility requirements it makes an exception for the file:// scheme where triple slashes (file:///...) are allowed. For any other scheme this is invalid.

I figure if parse_url supports file:// URIs it makes sense for Uri\build to support them too.

I tried to find a source for the proper behavior. RFC 3986 just says:

For example, the "file" URI scheme is defined so that no authority, an empty host, and "localhost" all mean the end-user's machine

[evert]

Interesting! I wonder if file: is exceptional, or if there's others like it. I want to do a bit of research about that before applying this patch, but everything looks good!

[matt-allan]

Thanks for the quick response 😄

I'm currently depending on the 1.x release. Should I open a separate PR targeting the 1.0 branch?

[evert]

I can do a backport. Takes only a few minutes.

[matt-allan]

Awesome 👌 thanks Evert!