formatting: make black --quiet in the example `hg fix` config I do like cake, but I cannot have so many of them.

formatting: remove the data-ogre from the config example Without he final `-`, black ignore the stdin and just looks at file provided as command line argument. Since `hg fix` feeds the file content through stdin and does not pass file argument, this meant black happily exited successful (all files passed as argument were formatted) without any output. Fix picked this "no output" as the new file content, deleting all previous content. I appreciate the fact this effectively removed all buggy code in any files processing that way, but this also ate all my data. The example config is now fixed in that regards.

py3: stop normalizing .encode()/.decode() arguments to unicode Now that we don't byte transform string literals, we no longer need this transform. While we're here, we also drop some superfluous u'' prefix in existing callers. Differential Revision: https://phab.mercurial-scm.org/D7011

py3: manually import pycompat.delattr where it is needed And with this change, we no longer need the auto-inserted import statement in the source transformer, so it has been removed! Differential Revision: https://phab.mercurial-scm.org/D7010

py3: manually import getattr where it is needed The march continues. Differential Revision: https://phab.mercurial-scm.org/D7009

py3: stop injecting pycompat.hasattr into modules I only found a single user of this pattern, probably because we use util.hasattr everywhere. Differential Revision: https://phab.mercurial-scm.org/D7008

py3: manually import pycompat.setattr where it is needed Continuing to eliminate the implicit import of symbols in the Python 3 source transformer so we can eliminate it. Differential Revision: https://phab.mercurial-scm.org/D7007

py3: stop implicitly importing unicode We should be pycompat.unicode everywhere. It turns out we were doing this everywhere except for one place in templatefilters! Differential Revision: https://phab.mercurial-scm.org/D7006

py3: manually import pycompat.open into files that need it We want to eliminate the source transformer. Currently it inserts a `from mercurial.pycompat import ...` at the top of files to alias some builtins. This commit replaces the implicit import of `open` with an explicit import on files that need it and changes the source transformer to no longer import `open`. As part of this, we needed to store an explicit local for `open` in the Python 2 code path in `pycompat` so the import works. (Builtins that are automatically in scope cannot be imported.) Differential Revision: https://phab.mercurial-scm.org/D7005

import-checker: allow symbol imports from mercurial.pycompat Currently, the source transformer inserts `from mercurial.pycompat import delattr, getattr, hasattr, setattr, open, unicode` to the top of every file. As part of getting rid of the source transformer, we'll need to have source code call these wrappers directly. Rather than rewrite all call sites to call pycompat.*, I think it makes sense to import needed symbols via explicit imports. That requires loosening the import checker to allow this. Differential Revision: https://phab.mercurial-scm.org/D7004