This re-enables the test that eval retains pgroups, from #6806.
The old version was racey and failed a lot. In the new version, we use
temp files to resolve the race.
Give string expansion an (optional) parent pgroup. This is threaded all
the way into eval(). This ensures that in a mixed pipeline like:
cmd | begin ; something (cmd2) ; end
that cmd2 and cmd have the same pgroup.
Add a test to ensure that command substitutions inherit pgroups
properly.
Fixes#6624
This test launches two background processes and is sensitive to
interleaving of output. Fix it so that newlines are not output by
the background process.
Hopefully this fixes the flakiness of this test.
If a background process runs a fish function which launches another
background process, ensure that these background procs get different
pgroups. Add a test for it.
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.
