Patch derived from discussion at https://savannah.nongnu.org/bugs/?37503

--- texi2html-5.0/texi2html.pl	2010-06-30 17:01:27.000000000 -0500
+++ texi2html-5.0/texi2html.pl	2014-07-09 01:17:57.062990582 -0500
@@ -2589,7 +2589,12 @@
     my $state = shift;
 
     # FIXME this should be done only once, for @documentencoding
-    my $encoding = lc(Texi2HTML::Config::get_conf('DOCUMENT_ENCODING'));
+    my $encoding;
+    my $input_encoding = Texi2HTML::Config::get_conf('documentencoding');
+    if (defined($input_encoding))
+    {
+      $encoding = lc($input_encoding);
+    }
     if (defined($encoding) and $encoding ne '' and exists($Texi2HTML::Config::t2h_encoding_aliases{$encoding}))
     {
        $encoding = $Texi2HTML::Config::t2h_encoding_aliases{$encoding};

Fix failures in test/encodings.

--- texi2html-5.0/texi2html.pl	2014-07-09 01:22:06.000000000 -0500
+++ texi2html-5.0/texi2html.pl	2014-07-10 23:23:47.182097602 -0500
@@ -53,6 +53,7 @@
 # for translations
 #use encoding 'utf8';
 #use utf8;
+binmode STDERR, ':encoding(utf8)';
 
 #
 # According to
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<div class='path'>path: <a href='/guix/log/?id=2c76e19df4b0b4aa0171f1edd9f240f7b6ba5b84'>root</a>/<a href='/guix/log/gnu?id=2c76e19df4b0b4aa0171f1edd9f240f7b6ba5b84'>gnu</a>/<a href='/guix/log/gnu/packages?id=2c76e19df4b0b4aa0171f1edd9f240f7b6ba5b84'>packages</a>/<a href='/guix/log/gnu/packages/m4.scm?id=2c76e19df4b0b4aa0171f1edd9f240f7b6ba5b84'>m4.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/m4.scm?id=2c76e19df4b0b4aa0171f1edd9f240f7b6ba5b84&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2018-08-25 16:23:36 +0200'>2018-08-25</span></td><td><a href='/guix/commit/gnu/packages/m4.scm?id=95895d53b06015fa74f07643cf98f86ae21551d7'>gnu: m4: Fix FTBFS with glibc &gt;= 2.28.</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2018-02-20 19:29:16 +0100'>2018-02-20</span></td><td><a href='/guix/commit/gnu/packages/m4.scm?id=05d86d70d9bc19d08716460f40976b74b97b6031'>gnu: m4: Update phase style.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2017-03-30 22:59:53 +0200'>2017-03-30</span></td><td><a href='/guix/commit/gnu/packages/m4.scm?id=84157bb8bf2c610584e0836047da4c710f8eaf76'>Merge branch 'master' into core-updates</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2017-03-30 01:30:16 +0200'>2017-03-30</span></td><td><a href='/guix/commit/gnu/packages/m4.scm?id=6fd52309b8f52c9bb59fccffac53e029ce94b698'>gnu: Use HTTPS for almost all gnu.org HOME-PAGEs.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>