This avoids possibly selecting Python 2.x on systems that have
both Python 2 and Python 3. We used to feel that what "python"
links to is a user choice that we should honor. However, we're
about to cease support for Python 2, so users will no longer have
any choice of that sort. This small change is being made ahead
of the big Python-2-ectomy so that we can see how much of the
buildfarm is not yet prepared for that. Systems with only
Python 2 will continue to build that way, for now.
Discussion: https://postgr.es/m/2872c9a0-4b0a-1354-d5f6-94d6f85ba354@enterprisedb.com
<!-- doc/src/sgml/README.links -->
Linking within DocBook documents can be confusing, so here is a summary:
Intra-document Linking
----------------------
<xref>
use to get chapter/section number from the title of the target
link, or xreflabel if defined at the target, or refentrytitle if target
is a refentry; has no close tag
http://www.oasis-open.org/docbook/documentation/reference/html/xref.html
linkend=
controls the target of the link/xref, required
endterm=
for <xref>, allows the text of the link/xref to be taken from a
different link target title
<link>
use to supply text for the link, only uses linkend, requires </link>
http://www.oasis-open.org/docbook/documentation/reference/html/link.html
can be embedded inside of <command>, unlike <xref>
External Linking
----------------
<ulink>
like <link>, but uses a URL (not a document target); requires
</ulink>; if no text is specified, the URL appears as the link
text
http://www.oasis-open.org/docbook/documentation/reference/html/ulink.html
url=
used by <ulink> to specify the URL, required
Guidelines
----------
- For an internal link, if you want to supply text, use <link>, else
<xref>.
- Specific nouns like GUC variables, SQL commands, and contrib modules
usually have xreflabels.
- For an external link, use <ulink>, with or without link text.
- xreflabels added to tags prevent the chapter/section for id's from being
referenced; only the xreflabel is accessible. Therefore, use xreflabels
only when linking is common, and chapter/section information is unneeded.
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