This may not be a bug per-se, but fish sure does like to try to get me to open emacs autosave files (those ending in '~').

Try this:

• mkdir /tmp/test
• cd /tmp/test
• touch foo.c foo.c~

• start typing ' emacs foo.c'

Notice that the suggestion is 'foo.c~', which is almost never the file I want to open.

I say it may not be a bug, because it may be easy for end-users to configure this problem away. But it seems like a poor out-of-the-box experience for emacs users, and is something I believe should be fixed in the default configuration.