The internal wiki link to a file using the optional second parameter does not yield expected results.
I do not currently see a bug listed in the bugzilla reports, assuming I was searching properly: tried, for example, "File", "File:", "Links", "Internal Links", "File Links", "Internal File", etc. I read through a lot of bugs but nothing seemed to immediately address this particular issue.
Start with facts I know:
*General internal link usage:
[[MyWikiPage]] => MyWikiPage
[[MyWikiPage|My Page]] => My Page
[[Media:MyMediaFile.png]] => Media:MyMediaFile.png
[[Media:MyMediaFile.png|My File]] => My File
Anything from that list would produce an anchor and display what's shown after the comment.
My concern is with the internal File: link. Now, I understand the File link is a loaded feature; with the additional ability to size an image for display, position, etc. I feel WM bugs out when the link does not link to a displayable file (i.e., an image). As an example:
*Internal File: links:
[[File:MyWikiFile.pdf]] => File:MyWikiFile.pdf
[[File:MyWikiFile.pdf|My File]] => File:MyWikiFile.pdf
In the second example, I feel (to remain consistent with other internal links) the anchor display text should be "My File" instead of "File:MyWikiFile.pdf".
I have to assume that since this is a rendering issue that it's all server side processing, so I don't think that operating system and browser matter. But just in case, XP Pro IE7.