merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/Documentation/git-sh-i18n.txt

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+git-sh-i18n(1)
+==============
+
+NAME
+----
+git-sh-i18n - Git's i18n setup code for shell scripts
+
+SYNOPSIS
+--------
+[verse]
+'. "$(git --exec-path)/git-sh-i18n"'
+
+DESCRIPTION
+-----------
+
+This is not a command the end user would want to run.  Ever.
+This documentation is meant for people who are studying the
+Porcelain-ish scripts and/or are writing new ones.
+
+The 'git sh-i18n scriptlet is designed to be sourced (using
+`.`) by Git's porcelain programs implemented in shell
+script. It provides wrappers for the GNU `gettext` and
+`eval_gettext` functions accessible through the `gettext.sh`
+script, and provides pass-through fallbacks on systems
+without GNU gettext.
+
+FUNCTIONS
+---------
+
+gettext::
+	Currently a dummy fall-through function implemented as a wrapper
+	around `printf(1)`. Will be replaced by a real gettext
+	implementation in a later version.
+
+eval_gettext::
+	Currently a dummy fall-through function implemented as a wrapper
+	around `printf(1)` with variables expanded by the
+	linkgit:git-sh-i18n{litdd}envsubst[1] helper. Will be replaced by a
+	real gettext implementation in a later version.
+
+GIT
+---
+Part of the linkgit:git[1] suite