bpo-29235: Make cProfile.Profile a context manager.

[ssanderson]

Add __enter__ and __exit__ methods to cProfile.Profile that call
enable() and disable(), respectively.

https://bugs.python.org/issue29235

[the-knights-who-say-ni]

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[ssanderson]

I believe I've signed the CLA now.

[matrixise]

@ssanderson thanks for the CLA but the validation is manual. we have to wait for the notification in the bug tracker :/ sorry, maybe @brettcannon could remove the CLA not signed, but you need to prove it. thanks again for your PR.

[ssanderson]

Ah, I see, I missed the note in the devguide saying to wait a day. Thanks for the heads up @matrixise!

[tiran]

@ssanderson Thanks for you PR.

The changeset is missing a news entry. Please follow https://devguide.python.org/committing/#what-s-new-and-news-entries and add a blurb.

[ssanderson]

@tiran updated with a news entry!

[ssanderson]

The travis failure here is in test.test_multiprocessing_forkserver.TestIgnoreEINTR. Naively, that seems unlikely to be related to this change?

ERROR: test_ignore (test.test_multiprocessing_forkserver.TestIgnoreEINTR)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/build/python/cpython/Lib/test/_test_multiprocessing.py", line 4359, in test_ignore
    os.kill(p.pid, signal.SIGUSR1)
ProcessLookupError: [Errno 3] No such process

[brettcannon]

The PR looks great, so I've just kicked off Travis again just to be safe/paranoid about the failure (but even if it fails again, @ssanderson , just ping this PR once Travis is finished so we don't forget to merge).

[ssanderson]

@brettcannon looks like travis is happy now.

[ssanderson]

(I noticed a small typo in the NEWS entry when looking at this again though).

[ssanderson]

I think this is good to merge. Anything else that's needed from me here?

[brettcannon]

Thanks for the patch, @ssanderson ! (And sorry for the delayed response; PyCon US recovery 😉 )

[ssanderson]

@brettcannon thanks for merging!