[PATCH v2] ci: use absolute PYTHON_PATH in the Linux jobs

In our test suite, when 'git p4' invokes a Git command as a subprocesses, then it should run the 'git' binary we are testing. Unfortunately, this is not the case in the 'linux-clang' and 'linux-gcc' jobs on Travis CI, where 'git p4' runs the system '/usr/bin/git' instead.

Travis CI's default Linux image includes 'pyenv', and all Python invocations that involve PATH lookup go through 'pyenv', e.g. our 'PYTHON_PATH=$(which python3)' sets '/opt/pyenv/shims/python3' as PYTHON_PATH, which in turn will invoke '/usr/bin/python3'. Alas, the 'pyenv' version included in this image is buggy, and prepends the directory containing the Python binary to PATH even if that is a system directory already in PATH near the end. Consequently, 'git p4' in those jobs ends up with its PATH starting with '/usr/bin', and then runs '/usr/bin/git'.

So use the absolute paths '/usr/bin/python{2,3}' explicitly when setting PYTHON_PATH in those Linux jobs to avoid the PATH lookup and thus the bogus 'pyenv' from interfering with our 'git p4' tests. Don't bother with special-casing Travis CI: while this issue doesn't affect the corresponding Linux jobs on GitHub Actions, both CI systems use Ubuntu LTS-based images, so we can safely rely on these Python paths.

Signed-off-by: SZEDER Gábor <szeder.dev@gmail.com>
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Junio, I see that you picked up the first/RFC version and applied it on top of v2.26.2. This patch won't work on v2.26.2, because its 'git p4' is not compatible with python3 yet.

 ci/lib.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)