[pushpop]

Is it really a “bug” if you’re writing incompatible code for Fish? Bug implies unexpected behaviour but I’d argue that Fish’s non-POSIX behaviour is well discussed, documented, and thus should be completely expected.

[rgoulter]

AFAIR the problems using fish tend to be when other programs (e.g. vim or whatever) try and interact with the shell and it's non-POSIX compliant.

The "expect it to work, didn't" is more on the user's side, going from e.g. bash to fish.

[pmarin]

I know it was just an example but on any Vi clone you can set the default shell:

   :set shell=/bin/bash