runtests: prefix with the testsuite and worker number

[IanButterworth]

Trying out showing the test suite name to make it easier to figure out

https://buildkite.com/julialang/julia-master/builds/52736#019b13f7-46fa-4266-8d65-b785869b9c06/954-1074

[gbaraldi]

What am I looking for as a difference

[IanButterworth]

It's not currently working

From worker 4: Precompiling packages...
From worker 4:     262.0 ms  ✓ Foo51989
From worker 4:   1 dependency successfully precompiled in 0 seconds

Should look like

loading (4): Precompiling packages...
loading (4):     262.0 ms  ✓ Foo51989
loading (4):  1 dependency successfully precompiled in 0 seconds

[IanButterworth]

It's working now https://buildkite.com/julialang/julia-master/builds/52735#019b13df-31dc-4b61-9713-b5692d6910da/943-1053

[IanButterworth]

I think it's looking good, but not sure if the changes to Distributed are the best way to do it i.e. via a global hook..
JuliaLang/Distributed.jl#157