py3: use pickle directly
pycompat.pickle abstracted over the different pickle modules in
Python 2 and 3. Now that we're Python 3 only, it is safe to use the
`pickle` module directly. So this commit does that.
As part of this we remove the rules from check-code.py that were
forbidden direct pickle module use.
We retain the `util.pickle` symbol for backwards compatibility, just
in case some extensions were using it.
Differential Revision: https://phab.mercurial-scm.org/D12249
Mercurial
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Mercurial is a fast, easy to use, distributed revision control tool
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Basic install::
$ make # see install targets
$ make install # do a system-wide install
$ hg debuginstall # sanity-check setup
$ hg # see help
Running without installing::
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