## Changes
`executor.Exec` now uses `cmd.CombinedOutput`. Previous implementation
was hanging on my windows VM during `bundle deploy` on the
`ReadAll(MultiReader(stdout, stderr))` line.
The problem is related to the fact the MultiReader reads sequentially,
and the `stdout` is the first in line. Even simple `io.ReadAll(stdout)`
hangs on me, as it seems like the command that we spawn (python wheel
build) waits for the error stream to be finished before closing stdout
on its own side? Reading `stderr` (or `out`) in a separate go-routine
fixes the deadlock, but `cmd.CombinedOutput` feels like a simpler
solution.
Also noticed that Exec was not removing `scriptFile` after itself, fixed
that too.
## Tests
Unit tests and manually
## Changes
Allow specifying executable in artifact section
```
artifacts:
test:
type: whl
executable: bash
...
```
We also skip bash found on Windows if it's from WSL because it won't be
correctly executed, see the issue above
Fixes#1159
## Changes
Instead of handling command chaining ourselves, we execute passed
commands as-is by storing them, in temp file and passing to correct
interpreter (bash or cmd) based on OS.
Fixes#1065
## Tests
Added unit tests
Andrew Nester
Ilia Babanov
Pieter Noordhuis