I can reproduce this.
Copying "http://example.com/url with space.html" from the address bar with CTRL+c and pasting with CTRL+v yields "http://example.com/url%20with%20spaces.html".
However, copying by highlighting text and pasting with middle mouse click, as per bug report, yields "http://example.com/url with space.html".
I can reproduce this.
Copying "http:// example. com/url with space.html" from the address bar with CTRL+c and pasting with CTRL+v yields "http:// example. com/url% 20with% 20spaces. html".
However, copying by highlighting text and pasting with middle mouse click, as per bug report, yields "http:// example. com/url with space.html".