censor: document that some commands simply ignore censored data I can't see a benefit for hg grep to ever error out early when it encounters censored data.

grep: warn on censored revisions instead of erroring out We need most of the grep logic to go through in case we encounter a censored revision, so we just return a None body for a censored node, and we stop just short of trying to record matches with the contents of that censored body. The other parts such as recording that the censored file has been considered at this revision needs to go into the proper dicts. I have also gotten weary of all the abbreviations, so while I did a small refactor to move the file-data-getting operation into a common function, I also expanded the abbreviations of the relevant variables within this little function. Hopefully some day this helps someone figure out what all the abbreviations mean. Although the censoring docs currently state that some commands error out or are ignored depending on the `censor.policy` config, I cannot see a benefit for grep to ever stop dead in its tracks when a censored revision is encountered. I will also amend the docs to indicate that some commands, such as grep, unconditionally ignore censored revisions.

py3: enable legacy fs encoding to fix filename compatibility on Windows This patch is untested. I just followed the instruction: https://docs.python.org/3/whatsnew/3.6.html#pep-529-change-windows-filesystem-encoding-to-utf-8

rust-cpython: run cargo fmt

rust-cpython: remove useless PyResult<> from leak_immutable() The caller should know if the shared data is mutably borrowed or not.

rust-cpython: remove useless PyRefMut wrapper

rust-cpython: drop manual management of mutably_borrowed RefCell::borrow() should guarantee there's no mutable borrow. As a follow up, maybe PySharedState can be a pure data structure + function. Most ref-sharing business has already been moved to PySharedRef* and PyLeaked*.