DISCUSS: Make --interleaved-output the default

[snoyberg]

A few different reasons:

1. People have been reporting issues about "frozen" compiles, when in fact it's just very large dependencies that take a long time to build. This output will make it clear that work is happening, just slowly.
2. I've had CI timeouts in the past due to lack of output for 10 minutes. Basically, same as 1, but impatient machines instead of impatient humans
3. It can be informative to see the output as it happens

Downsides:

1. Subjectively more confusing
2. Arguably people don't want to see the individual modules compiling for each dependency

CC @nh2

[Wildsoft]

Maybe indicate some progress in some other way to avoid confusing output

[NorfairKing]

I'd like --interleaved-output for local packages but not for dependencies, by default.
Or that --test implies --interleaved-output if there are multiple packages.

[snoyberg]

Maybe indicate some progress in some other way to avoid confusing output

Two problems with this:

1. We'd need to know what "some other way" is. In other words: can you be a bit more specific?
2. It doesn't exist yet, so would have to be implemented

I'd like --interleaved-output for local packages but not for dependencies, by default.

I get the motivation here. However, it wouldn't address my "frozen compiles" concern above. Not eliminating the possibility, just pointing out a limitation.

[snoyberg]

We can continue to refine the behavior up until the next release, but I've opened up a PR to change the default. This may also flush out some additional problems during testing. #4718