http_request_create_absolute_url() ignore last path in $base_url

Add tests.
Make functions results more expected.

If you still have questions, just look '/tests/http_request.test', after patch apply.
If somebody can add more test-cases, it would be great.

Yes I am, and also some contrib modules use this function: Feeds Crawler.

I wonder if it could break any existing workflows

I hope not, all test are passed.

// Now it can be several '..' in url.
http_request_create_absolute_url('../../d', 'http://www.example.com/a/b/c/');
// before http://www.example.com/a/b/d
// now    http://www.example.com/a/d

// Also it depends if base url have trailing slash or not.
http_request_create_absolute_url('d', 'http://www.example.com/a/');
// before http://www.example.com/d
// now    http://www.example.com/a/d

http_request_create_absolute_url('d', 'http://www.example.com/a');
// before http://www.example.com/d
// now    http://www.example.com/d

// And now it process $url even if it starts with /.
http_request_create_absolute_url('/d/./j/k/../l/', 'http://www.example.com/a');
// before http://www.example.com/d/./j/k/../l
// now    http://www.example.com/d/j/l

Well, I should find time to take a closer look at it.

I think most easy way to see difference, run tests from the patch for curent version in 7.x-2.x and this patched version.

But there are some more bugs/features. I not sure about them. But I think if we wouldn't fix them, it's better to update comment for this function.

// mailto: skype: magnet: in $url and 
http_request_create_absolute_url('mailto:bob@example.com', 'http://example.com/');
// now http://example.com/mailto:bob@example.com
// should be false or use rawurlencode http://example.com/mailto%3Abob%40example.com

// Non ascii chars
http_request_create_absolute_url('Яд', 'https://ru.wikipedia.org/wiki/');
// now false
// should be https://ru.wikipedia.org/wiki/%D0%AF%D0%B4