Back-port part of 1.128 from the trunk:

\productioncont:  Replace leading spaces with   so that it's
    possible to control the indentation of continuation lines.

Doc/perl/python.perl

@@ -808,6 +808,7 @@ sub do_cmd_production{
 sub do_cmd_productioncont{
     local($_) = @_;
     my $defn = next_argument();
+    $defn =~ s/^( +)/' ' x length $1/e;
     return ("<tr valign=\"baseline\">\n"
             . "    <td>&nbsp;</td>\n"
             . "    <td>&nbsp;</td>\n"