Use explicit bash shell with pipefail semantics in GitHub actions

[nickpdemarco]

According to the GitHub Documentation, the shell for Unix platforms when unspecified is bash -e {0}. Notably, this does not set pipefail.

Because pipefail was not set, the pipe to tee was swallowing any error codes during the test run. This PR explicitly sets shell: bash for all run commands, which (per the above docs) produces the internal command bash --noprofile --norc -eo pipefail {0}.

It is baffling that the implicit, default bash shell has different semantics from the explicit bash shell.

[dabrahams]

Overall, great work discovering the truth about the shells (which information I'd been unable to find).

Please think about my questions. Also think about whether we want to remove the top-level &&s.
Finally, remember I asked that you put documentation about whatever you learned into the .yml file?

[dabrahams]

Why is this one set -o pipefail and the other one shell: bash?
If shell: bash doesn't work in this context, we should use explicit sets everywhere.

Do we not also want set -e? Let's just be as explicit as possible.

[nickpdemarco]

Here, we're leveraging a custom GitHub action which does not support a shell argument. It probably should, so I raised an issue. For now, I'll be explicit in all steps for consistency, as you ask.

[dabrahams]

@nickpdemarco Do we need to chat to get this moving forward?

[nickpdemarco]

@dabrahams sorry, no - I got distracted by the compiler explorer work. I'll address your comments now.

[dabrahams]

@nickpdemarco it looks like a test is still disabled in this PR? Please merge once you've fixed that!