dirstatemap: add a common `_drop_entry` method for dirstatemap
This method is called to remove DirstateItem from the map.
Each variant have a different implementation (which is … the point).
Differential Revision: https://phab.mercurial-scm.org/D11577
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
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Running without installing::
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Notes for packagers
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Mercurial ships a copy of the python-zstandard sources. This is used to
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