The link does not seem to be convenient for actually seeing the attachment.
The 'edit' view contains an area for attachments who's mime types are renderable in a browser to be displayed.
The attachment mentioned is set to text/plain, and it renders correctly in the browser, at that URL, correctly.
My guess is that this issue is related to 'mixed content' between the main Bugzilla (https), and the attachments host (http).
My browser (Firefox 440b9 Beta) blocks this mixed content by default, and I believe a number of other browsers do, but other browsers do not.
We'll have to solve this properly in the long term, but in the short term, bugzilla 'is' working as expected, correctly, that is; attachments that can be displayed, are displayed in the 'edit' view.
Created attachment 165864 [details]
Screenshot of edit view rendering attachment
@Andriy, can you confirm whether it's the browser blocking mix-content that's causing the attachment not to be displayed?
(In reply to Kubilay Kocak from comment #3)
That sounds plausible although I am not sure how to confirm that.
I'll attach a screenshot of what I am seeing.
OTOH, I am still not convinced that the notification emails should contain the edit link. How likely is it that a person watching a bug would like to edit someone else's attachment? As opposed to just taking a look at it.
Created attachment 165867 [details]
attachment edit view
This is how I see the attachment editing page accessed via a link in a bugzilla-generated email.
(In reply to Andriy Gapon from comment #4)
I know and understand what you mean by edit not seeming like the right thing to do. I'll leave that as an open consideration for improvement. Having said that 'edit' in this context is unfortunately a terrible name for the view :)
Created attachment 165868 [details]
mixed content blocking (firefox 44 beta)
My browser wasn't showing things in the preview pane either for the example bug referenced. I confirmed viewing worked fine when disabling the mixed content blocking.
Attached is what I saw
Yes, I see now the icon telling that "Firefox blocked parts of this page that are not secure".
This is partially resolved by bug 204374 (making attachment viewing actually work by resolving mix-content warnings), but this issue will remain open to consider updating email templates to use URL's pointing to view attachment, not the edit view.