Additional information: Requesting the above https URL, it seems like the sourceforge server provides a http redirect.

Copying it to the clipboard and opening via Klipper in Firefox works, resulting in:
http://sourceforge.net/tracker/?func=detail&atid=106488&aid=2162955&group_id=6488

So may be the subject should be: HTTP redirect does not work (which could lead this bug to be a duplicate of another one).

I just tried directly clicking on that link (using konqueror from 4.1.2 as well) and I can't reproduce. Do you see this behaviour only if clicking the link in the mail (kmail?) or also if clicking it in konqueror (eg. from this website)?

@Michael: It doesn't work even if I click on the link above in Konqueror directly. In general, I cannot open any sourceforge.net secured site, there is always the same problem.
It could be interesting for you that I'm behind a proxy. I get always a
---
The requested URL could not be retrieved
 While trying to retrieve the URL: http://sourceforge.nethttps//sourceforge.net/account/login.php 
 The following error was encountered: 
 Unable to determine IP address from host name for sourceforge.nethttps 
 The dnsserver returned: 
 Name Error: The domain name does not exist. 
 This means that: 
 The cache was not able to resolve the hostname presented in the URL. 
 Check if the address is correct. 

Your cache administrator is webmaster. 
 
 Generated Fri, 31 Oct 2008 07:58:22 GMT by proxy (squid/2.5.STABLE5)
---

... and the reason why this seems to be Konqueror-specific is:
Opening the same link works as in Firefox 3.0.3 and Opera 9.61 (over the same proxy).

This seems to be a proxy-only problem. I can confirm this bug using a squid proxy. I've been trying to reproduce this using my own server but didn't manage to do so:

Made a redirection https://test.confuego.org/173950 => http://test.confuego.org/173950 and it works without any problems.

I created some debug output using wget and the proxy connecting to the https://* addresses. Please note that I stripped the proxy connection (same anyway) and the successive request.

---test.confuego.org---
GET /173950/?func=detail&atid=106488&aid=2162955&group_id=6488 HTTP/1.0
User-Agent: Wget/1.10.2                                                
Accept: */*                                                            
Host: test.confuego.org                                                

HTTP/1.1 302 Found                               
Date: Fri, 31 Oct 2008 09:15:21 GMT              
Server: Apache/2.2.3 (Debian) DAV/2 SVN/1.4.2 PHP/5.2.0-8+etch11 mod_ssl/2.2.3 OpenSSL/0.9.8c
Location: http://test.confuego.org/173950/?func=detail&atid=106488&aid=2162955&group_id=6488 
Content-Length: 425                                                                          
Connection: close                                                                            
Content-Type: text/html; charset=iso-8859-1                                                  
-----------------------

----sourceforge.net----
GET /tracker/?func=detail&atid=106488&aid=2162955&group_id=6488 HTTP/1.0
User-Agent: Wget/1.10.2                                                 
Accept: */*                                                             
Host: sourceforge.net                                                   

HTTP/1.0 302 Found                               
Connection: close                                
X-Powered-By: PHP/5.2.6                          
X-SFX-Webhead: sfs-web-6                         
X-SFX-Revision: release_20081022.02              
Location: http://sourceforge.net/tracker/?func=detail&atid=106488&aid=2162955&group_id=6488
Content-type: text/html                                                                    
Date: Fri, 31 Oct 2008 09:16:33 GMT                                                        
Server: lighttpd/1.4.19                                                                    
Vary: Accept-Encoding, User-Agent                                                          
-----------------------

Lemma: which version did you confirm this with?

I could only confirm it on 4.1.2. I was about to try it on trunk as soon as my build is done.

As in the header at the beginning of this thread: 4.1.2, too, maybe with some patches of OpenSUSE towards 4.1.3.

I can now confirm for trunk r875700 as well. Same behaviour as in the original report.

Possibly related: bug 171256

SVN commit 882074 by ahartmetz:

 - Only send protocol, host and port of resource when necessary.
 - Clean up some proxy-related code to make similar things look similar.
BUG:173950



 M  +9 -17     http.cpp  


WebSVN link: http://websvn.kde.org/?view=rev&revision=882074

Works for me in KDE 4.2.0, thank you.