Detect when $fisher_path = $fisher_config and exit with error message

[9999years]

The fishfile is stored at $fisher_path/fishfile, and _fisher_commit executes rm -rf $fisher_config, so if $fisher_path = $fish_config, running fisher will delete the fishfile before looking for packages, leading to confusing errors.

Adds a check to fisher, exiting with a message like

$fisher_path (/home/arvensis/.config/fisher) cannot be /home/arvensis/.config/fisher
Consider instead:
    set -g fisher_path "$HOME/.config/fisher_local"

To prevent user confusion in the future.

[jorgebucaran]

@9999years I don't believe using readlink is cross-Unix compatible?

[jorgebucaran]

@9999years I see what's going on here. I suppose you run into this, hence the desire to add a check, but I suspect $fisher_path being equal to $fish_config is an oddity. Can't back up my claim, though, so who knows?

For starters, we 'd need to switch from readlink to something compatible across Unices. The realpath builtin is the easy way out, but that means dropping support for a bunch of older fish.

On the other hand, a comment in the docs might be the next best thing to do here. Thoughts?

[reitzig]

I suspect $fisher_path being equal to $fish_config is an oddity. Can't back up my claim, though, so who knows?

Don't you always set it, though?

set -q fisher_path; or set -g fisher_path $fish_config

Not sure how $fisher_path could have been set already at that point. But then, I also don't understand why that line makes sense, so maybe I'm missing something fundamental here.

[jorgebucaran]

Hi @9999years, sorry for the late reply. Would you mind checking if this is still issue in fisher@3.2.12?

[jorgebucaran]

Not going to merge here, but I'll revisit this issue when I start working on #582.