Improve handling of exit codes from bash command execution

[Martin]

We run bash commands in a few different places, e.g. to execute git commands or to execute the build commands for a provider.

Currently I don't think handle the exit codes of those commands. We should verify first if this is the case
Hence, when the build command of a provider fails, we can see this in the build log, but the exit code is not handled.
This is important to have blackbox test which fail when an internal bash command fails.

[Martin]

Handling of exit codes whenever a bash command is executed was introduced with bf729f8

Whenever a bash command exits with not 0, an error is thrown.