commit d95bfbded2466bb6ea796254f3f271a73505993b
author Ryan Beasley <beasleyr@vmware.com> Fri May 01 12:16:34 2020 -0700
committer Copybara-Service <copybara-worker@google.com> Fri May 01 12:17:54 2020 -0700
tree 248be89f67585338a50be2561f1284e8ec646d1b
parent 3862f87ac4fdf567525dc77d78b73c0c4f473647

Reintroduce support for Python 2.6 to python_stub_template

Commit d5012a7ed19c1e75e413373fa22c5f1b08a9ee29 introduced a Python
2.7 dependency into python_stub_template.txt.  Unfortunately this stub
is non-hermetic, so even if the user has configured Python 2.7 and 3
`py_runtime`s, their builds may fail if the system-provided Python is ancient
(ex: CentOS 6.6 provides Python 2.6.6).

Accommodate ancient Python by reworking the path deduplication in terms
of a `set` and a generator instead of `collections.OrderedDict`.

Workaround for #11265.

Testing Done:
- `bazelisk test //src/test/shell/integration:python_stub_test`
- In a CentOS 6.6 env:
```console
$ /usr/bin/env python -V
Python 2.6.6
$ cat >test.py <<EOF
import sys
print(sys.executable)
EOF
$ cat >BUILD <<EOF
py_binary(name = "test", srcs = ["test.py"])
EOF
$ bazel run :test
/path/to/my/hermetic/python3
```

Closes #11269.

PiperOrigin-RevId: 309450777