hgdemandimport: disable on Python 3.5
The demand importer functionality isn't working at all on Python 3.5.
I'm not sure what's wrong.
Since it isn't working, let's disable it completely.
```
$ HGRCPATH= hyperfine -w 1 -r 50 -- "~/.pyenv/versions/3.5.9/bin/python ./hg version" \
"HGDEMANDIMPORT=disable ~/.pyenv/versions/3.5.9/bin/python ./hg version"
Benchmark #1: ~/.pyenv/versions/3.5.9/bin/python ./hg version
Time (mean ± σ): 163.7 ms ± 2.2 ms [User: 148.5 ms, System: 15.7 ms]
Range (min … max): 161.0 ms … 170.2 ms 50 runs
Benchmark #2: HGDEMANDIMPORT=disable ~/.pyenv/versions/3.5.9/bin/python ./hg version
Time (mean ± σ): 164.3 ms ± 1.4 ms [User: 148.2 ms, System: 16.6 ms]
Range (min … max): 161.4 ms … 169.8 ms 50 runs
```
Differential Revision: https://phab.mercurial-scm.org/D7953
Mercurial evolves over time, some features, options, commands may be replaced by
better and more secure alternatives. This topic will help you migrating your
existing usage and/or configuration to newer features.
Commands
========
The following commands are still available but their use are not recommended:
``locate``
This command has been replaced by `hg files`.
``parents``
This command can be replaced by `hg summary` or `hg log` with appropriate
revsets. See `hg help revsets` for more information.
``tip``
The recommended alternative is `hg heads`.
Options
=======
``web.allowpull``
Renamed to `allow-pull`.
``web.allow_push``
Renamed to `allow-push`.