infinitepush: drop logic related to treemanifest extension
treemanifest is another facebook's extension which is not in core. Let's drop
the logic related to infinitepush extension which is now ported to core.
Differential Revision: https://phab.mercurial-scm.org/D2106
Mercurial
=========
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::
$ make local # build for inplace usage
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See https://mercurial-scm.org/ for detailed installation
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