Firefox suggests output.log for download instead of showing it in the iframe

[blipp]

When I visit the page of a GitHub-Repository on the ShareLaTeX GitHub LaTeX CI, namely something like https://www.sharelatex.com/github/repos/…/…, Firefox wants to download the logfile output.log instead of showing it in an iframe, like in Chrome.

I am running Firefox 38.0.5 on Arch Linux. Tested with a fresh Firefox profile.

[Travis-S]

Experienced similar issue here. Running Firefox 40.0 on Linux Mint 17.1.