I'm sending the file via a html form, the mime type is set to text/tab-separated-values automatically (or text/plain respectively).
I would have expected that the parser would just parse .tsv as plain text if there is no parser implemented for .tsv. I just saw that text/tab-seperated-values is not a supportet content-type content-types.R and therefore it falls back to 'application/octet-stream'.
Of course, getting a data.frame directly would be great! I'll try to have a look at the code and see if I can make a PR.
Thanks for your help!