Okay this is irrelevant to the discussion but I just typed in `github/mevdschee/2048.c` in the address bar expecting Firefox to perform a Google search but it instead lead me to the repo! What!
If you type something that is not a valid/existing domain, Firefox will try to append .com and/or prepend www. in an attempt to get a valid domain. If that fails, it will do a search.
You can configure this via browser.fixup.alternate.* in about:config.
