pydoc topics, keywords and symbols always use pager instead of output

[eht16]

BPO	37755
Nosy	@eht16
PRs	bpo-37755: Use configured output in pydoc instead of pager #15105

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = None
created_at = <Date 2019-08-04.12:48:20.274>
labels = ['3.8', 'type-bug', 'library']
title = 'pydoc topics, keywords and symbols always use pager instead of output'
updated_at = <Date 2019-08-04.12:55:23.691>
user = 'https://github.com/eht16'

bugs.python.org fields:

activity = <Date 2019-08-04.12:55:23.691>
actor = 'eht16'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2019-08-04.12:48:20.274>
creator = 'eht16'
dependencies = []
files = []
hgrepos = []
issue_num = 37755
keywords = ['patch']
message_count = 1.0
messages = ['348983']
nosy_count = 1.0
nosy_names = ['eht16']
pr_nums = ['15105']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue37755'
versions = ['Python 3.8']

[eht16]

I noticed a probably unintended behavior in help() usage:

when an output is set on pydoc.Helper(), most of its methods
use this output instead of a pager.
But 'True', 'False' and 'None' as well as all topics, keywords
and symbols always use a pager instead of the configured output.

My use case is to use the pydoc help system to display help contents
in Geany (a text editor) in a graphical manner
(and so I cannot make any use of a pager).

Example code:

#!/usr/bin/env python3
# -- coding: utf-8 --

from io import StringIO
import pydoc
import sys


if __name__ == '__main__':
    help_text = StringIO()

    helper = pydoc.Helper(output=help_text)
    # help contents are written to help_text as expected
    helper.help('pydoc')

    # the following calls each show the help contents in a pager instead
    # of using the configured output
    helper.help('True')
    helper.help('False')
    helper.help('None')
    helper.help('**')  # symbol example
    helper.help('SEQUENCES')  # topic example
    helper.help('await')  # keyword example

Tested against Python 3.7.3.

[serhiy-storchaka]

Thank you for your contribution @eht16. Sorry it took so long to review and merge your PR.

[eht16]

It took me to answer almost as long :D.
Thank you for the review.