This prevents a seemingly infinite loop in
fish -c 'alias ssh "env ssh"; complete -C "ssh "'
It still prints "maximum recursion depth exceeded", but a follow-up commit
will work around that.
Fixes#7389
It's now good enough to do so.
We don't allow grid-alignment:
```fish
complete -c foo -s b -l barnanana -a '(something)'
complete -c foo -s z -a '(something)'
```
becomes
```fish
complete -c foo -s b -l barnanana -a '(something)'
complete -c foo -s z -a '(something)'
```
It's just more trouble than it is worth.
The one part I'd change:
We align and/or'd parts of an if-condition with the in-block code:
```fish
if true
and false
dosomething
end
```
becomes
```fish
if true
and false
dosomething
end
```
but it's not used terribly much and if we ever fix it we can just
reindent.
This completed the commandline with options removed, which looked like
env VAR=VAL command option
Which didn't really actually work.
Fixes#5856.
[ci skip]
