* dd/test-with-busybox:
  t5703: feed raw data into test-tool unpack-sideband
  t4124: tweak test so that non-compliant diff(1) can also be used
  t7063: drop non-POSIX argument "-ls" from find(1)
  t5616: use rev-parse instead to get HEAD's object_id
  t5003: skip conversion test if unzip -a is unavailable
  t5003: drop the subshell in test_lazy_prereq
  test-lib-functions: test_cmp: eval $GIT_TEST_CMP
  t4061: use POSIX compliant regex(7)

* dd/ci-musl-libc:
  travis: build and test on Linux with musl libc and busybox
  ci/linux32: libify install-dependencies step
  ci: refactor docker runner script
  ci/linux32: parameterise command to switch arch
  ci/lib-docker: preserve required environment variables
  ci: make MAKEFLAGS available inside the Docker container in the Linux32 job

This should help with adding new CI-specific if-else arms.

Signed-off-by: Johannes Schindelin <[email protected]>
Signed-off-by: Đoàn Trần Công Danh <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

For each CI system we support, we need a specific arm in that if/else
construct in ci/lib.sh. Let's add one for GitHub Actions.

Signed-off-by: Johannes Schindelin <[email protected]>
Signed-off-by: Đoàn Trần Công Danh <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

GitHub Action doesn't set TERM environment variable, which is required
by "tput".

Fallback to dumb if it's not set.

Signed-off-by: Đoàn Trần Công Danh <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

In 6cdccfc (i18n: make GETTEXT_POISON a runtime option,
2018-11-08), the `jobname` was adjusted to have the `GIT_TEST_` prefix,
but that prefix makes no sense in this context.

Co-authored-by: Đoàn Trần Công Danh <[email protected]>
Signed-off-by: Johannes Schindelin <[email protected]>
Signed-off-by: Đoàn Trần Công Danh <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

In a later patch, we will support GitHub Action.

Explicitly install all of our build dependencies on Linux.
Since GitHub Action's Linux VM hasn't installed our build dependencies.
And there're no harm to reinstall them (in Travis)

Signed-off-by: Đoàn Trần Công Danh <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

In a later patch, we will run Documentation job in GitHub Actions.
The job will run without elevated permission.

Run `gem` with `sudo` to elevate permission in order to be able to
install to system location.
This will also keep this installation in-line with other installation in
our Linux system for CI.

Signed-off-by: Johannes Schindelin <[email protected]>
[Danh: reword commit message]
Signed-off-by: Đoàn Trần Công Danh <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

This patch adds CI builds via GitHub Actions. While the underlying
technology is at least _very_ similar to that of Azure Pipelines, GitHub
Actions are much easier to set up than Azure Pipelines:

- no need to install a GitHub App,

- no need to set up an Azure DevOps account,

- all you need to do is push to your fork on GitHub.

Therefore, it makes a lot of sense for us to have a working GitHub
Actions setup.

While copy/editing `azure-pipelines.yml` into
`.github/workflows/main.yml`, we also use the opportunity to accelerate
the step that sets up a minimal subset of Git for Windows' SDK in the
Windows-build job:

- we now download a `.tar.xz` stored in Azure Blobs and extract it
  simultaneously by calling `curl` and piping the result to `tar`,

- decompressing via `xz`,

- all three utilities are installed together with Git for Windows

At the same time, we also make use of the matrix build feature, which
reduces the amount of repeated text by quite a bit.

Also, we do away with the parts that try to mount a file share on which
`prove` can store data between runs. It is just too complicated to set
up, and most times the tree changes anyway, so there is little return on
investment there.

Initial-patch-by: Johannes Schindelin <[email protected]>
Signed-off-by: Johannes Schindelin <[email protected]>
Signed-off-by: Đoàn Trần Công Danh <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Signed-off-by: Johannes Schindelin <[email protected]>
Signed-off-by: Đoàn Trần Công Danh <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

We have GitHub Actions now. Running the same builds and tests in Azure
Pipelines would be redundant, and a waste of energy.

Signed-off-by: Johannes Schindelin <[email protected]>
Signed-off-by: Đoàn Trần Công Danh <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

…umber

When a test fails, it is nice to see where the corresponding code lives
in the worktree. Sadly, it seems that only Bash allows us to infer this
information. Let's do it when we detect that we're running in a Bash.

This will come in handy in the next commit, where we teach the GitHub
Actions workflow to annotate failed test runs with this information.

Signed-off-by: Johannes Schindelin <[email protected]>
Signed-off-by: Đoàn Trần Công Danh <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

With this patch, test failures will be annotated with a helpful,
clickable message in GitHub Actions. For details, see
https://github.com/actions/toolkit/blob/master/docs/problem-matchers.md

Note: we need to set `TEST_SHELL_PATH` to Bash so that the problem
matcher is fed a file and line number for each test failure.

Signed-off-by: Johannes Schindelin <[email protected]>
Signed-off-by: Đoàn Trần Công Danh <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Arguably, CI builds' most important task is to not only identify
regressions, but to make it as easy as possible to investigate what went
wrong.

In that light, we will want to provide users with a way to inspect the
tests' output as well as the corresponding directories.

This commit adds build steps that are only executed when tests failed,
uploading the relevant information as build artifacts. These artifacts
can then be downloaded by interested parties to diagnose the failures
more efficiently.

Signed-off-by: Johannes Schindelin <[email protected]>
Signed-off-by: Đoàn Trần Công Danh <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>