futures: switch to absolute and relative imports This makes the package conform with our importing policy, silencing a number of warnings. It also makes the package usable when it isn't named "concurrent.futures." Differential Revision: https://phab.mercurial-scm.org/D3264

tests: silence pyflakes for thirdparty/concurrent It is complaining about unused imports. Differential Revision: https://phab.mercurial-scm.org/D3263

futures: get rid of extend_path This is used so mutliple directories can provide a package. We don't need it when vendoring. Differential Revision: https://phab.mercurial-scm.org/D3262

thirdparty: vendor futures 3.2.0 Python 3 has a concurrent.futures package in the standard library for representing futures. The "futures" package on PyPI is a backport of this package to work with Python 2. The wire protocol code today has its own future concept for handling of "batch" requests. The frame-based protocol will also want to use futures. I've heavily used the "futures" package on Python 2 in other projects and it is pretty nice. It even has a built-in thread and process pool for running functions in parallel. I've used this heavily for concurrent I/O and other GIL-less activities. The existing futures API in the wire protocol code is not as nice as concurrent.futures. Since concurrent.futures is in the Python standard library and will presumably be the long-term future for futures in our code base, let's vendor the backport so we can use proper futures today. # no-check-commit because of style violations Differential Revision: https://phab.mercurial-scm.org/D3261

py3: make sure decode() first argument is str Uses pycompat.sysstr() to make sure we uses bytes on Python 2 and unicodes on Python 3. Differential Revision: https://phab.mercurial-scm.org/D3279

patch: make extract() a context manager (API) Previously, this function was creating a temporary file and relying on callers to unlink it. Yuck. We convert the function to a context manager and tie the lifetime of the temporary file to that of the context manager. This changed indentation not only from the context manager, but also from the elination of try blocks. It was just easier to split the heart of extract() into its own function. The single consumer of this function has been refactored to use it as a context manager. Code for cleaning up the file in tryimportone() has also been removed. .. api:: ``patch.extract()`` is now a context manager. Callers no longer have to worry about deleting the temporary file it creates, as the file is tied to the lifetime of the context manager. Differential Revision: https://phab.mercurial-scm.org/D3306