Created attachment 786987 [details]
Request-response pair exported from F12 tool in IE11 showing headers used
User Agent: HTML5
Steps to reproduce:
I clicked the Search tab on this Bugzilla, selected "all" and entered "internet explorer" to the search field, then pressed enter to search this Bugzilla for all bugs related to Internet Explorer 11.
Bugzilla sent the results back to IE11, which offered to save it to a file named buglist. Examining the HTTP traffic shows that Bugzilla was using multipart/x-mixed-replace as a Content-Type, which isn't part of HTML5 and doesn't appear to be standardized anywhere at all.
Bugzilla should have sent the results back using regular HTML5. If asynchronously loaded results are needed for better user experience Bugzilla should have used Server-Sent Events with AJAX fallback for browsers where S-SE are not available.
Using F12 Developer Tools to use a custom user-agent like "HTML5" instead of the default "Mozilla/5.0 (Windows NT 6.3; WOW64; Trident/7.0; rv:11.0) like Gecko" and everything else being the same leads to the search working correctly.
Created attachment 786988 [details]
Search results received by IE11
Bugzilla uses HTML 4.01 Transitional, not HTML5, and so doesn't use Server-Sent Events which is part of HTML5. And per http://en.wikipedia.org/wiki/Server-sent_events, Internet Explorer doesn't support this technology anyway.
IE11 gets multipart/x-mixed-replace because its UserAgent string doesn't follow older versions of IE, i.e. both "MSIE" and "compatible" are gone. This breaks our detection of the browser.
Also note that if IE11 UserAgent string contains "like Gecko", then IE11 should work like Gecko, i.e. support the server-push technology. As suggested on http://msdn.microsoft.com/en-us/library/ie/bg182625%28v=vs.85%29.aspx, we should look for "Trident" to detect IE.
Created attachment 787053 [details] [diff] [review]
Trident is present in the UserAgent string since IE8.
Comment on attachment 787053 [details] [diff] [review]
Review of attachment 787053 [details] [diff] [review]:
We were just discussing this on IRC, the reasoning for putting this on the 4.2 and 4.0 branches also is because these branches will still be supported when IE11 releases, and major browser compatibility issues are a big deal.
Committing to: bzr+ssh://firstname.lastname@example.org/bugzilla/trunk/
Committed revision 8698.
Committing to: bzr+ssh://email@example.com/bugzilla/4.4/
Committed revision 8593.
Committing to: bzr+ssh://firstname.lastname@example.org/bugzilla/4.2/
Committed revision 8223.
Committing to: bzr+ssh://email@example.com/bugzilla/4.0/
Committed revision 7755.
Created attachment 8342904 [details]
Ianiey: Do NOT use bugzilla.mozilla.org for testing, as this is a production Bugzilla!
Use https://landfill.bugzilla.org/ for testing Bugzilla instead!
Comment on attachment 8342904 [details]
Some bmo admin please delete this attachment.
The content of attachment 8342904 [details] has been deleted for the following reason:
I am also seeing this issue still on v4.4
(In reply to admin from comment #12)
> I am also seeing this issue still on v4.4
please file a new bug if you think this issue has not been fixed. make sure you include both the bugzilla and IE versions.