I think this has happened before. I maintain a spellchecking extension (http://extensions.libreoffice.org/extension-center/an-dearbhair-beag-scottish-gaelic-spellchecker) and the file I (always) upload is most definitely a .oxt file but when the file downloads, it appends a -1 (i.e. it becomes .oxt-1) which renders the file unusable. Of course I can remove the -1 and then it works fine but I cannot communicate this to all users who may download the extension. I have just uploaded a new version to see if I missed a setting somewhere but it just uploads the .oxt and downloads it as an .oxt-1
Andreas - thought this might interest you. If not, apologies for the noise :)
I looked over the downloadable files and couldn't find such an issue in the portal_catalog index. I tried then with a new downloadable file (3-0a.oxt) at the release 3.0 of the spellchecker and everything was fine (no additional -1). There are two options that could cause the issue: a) there is already a file with the same name on the website (I can't find that file in the catalog yet) b) the file has the same name on the local hard-disk before the upload. There seemed to be no files with an -1 at the end in this spell checking project but the version 3.0.
Created attachment 120242 [details] screeenshot of oxt file in directory I wish it was just a misnamed file at my end but I've set Windows up to show extensions and as you can see in the screenshot, there is no -1 at the end.
Bugs with the sites now belong on http://redmine.documentfoundation.org/ If there's still something you'd like to see rectified regardin this, or the bug occurs again, please open a ticket there.
Marking as fixed, the issue seems to have gone away.
Since there is no specific commit fixing this issue, setting to WORKSFORME. FIXED is used only when a commit exists. Feel free to reopen this issue if you still can reproduce this particular problem or if I did miss something peculiar.