Make sure deleted tag pages don't get recreated.

The reason to do this is basically a user interaction design decision.

It is achieved by adding an entry, associated to the creating plugin, to
%pagestate. To find out if files were deleted a new global hash %del_hash is
%introduced.

IkiWiki.pm

@@ -14,7 +14,7 @@ use open qw{:utf8 :std};
 use vars qw{%config %links %oldlinks %pagemtime %pagectime %pagecase
 	    %pagestate %wikistate %renderedfiles %oldrenderedfiles
 	    %pagesources %destsources %depends %depends_simple %hooks
-	    %forcerebuild %loaded_plugins @autofiles};
+	    %forcerebuild %loaded_plugins %autofiles %del_hash};
 
 use Exporter q{import};
 our @EXPORT = qw(hook debug error template htmlpage deptype
@@ -1895,17 +1895,28 @@ sub add_link ($$) {
 		unless grep { $_ eq $link } @{$links{$page}};
 }
 
-sub add_autofile ($) {
+sub add_autofile ($$) {
 	my $autofile=shift;
+	my $plugin=shift;
 
 	if (srcfile($autofile, 1)) {
 		return 0;
 	}
 
 	my ($file, $page) = verify_src_file("$config{srcdir}/$autofile", $config{srcdir});
-	if (defined $file) {
-		push @autofiles, $file;
+
+	if ((!defined $file) ||
+	(exists $pagestate{$page}{$plugin}{autofile_deleted})) {
+		return 0;
 	}
+
+	if (exists $del_hash{$file}) {
+		$pagestate{$page}{$plugin}{autofile_deleted}=1;
+		return 0;
+	}
+
+	$autofiles{$file}=$plugin;
+	return 1;
 }
 
 sub pagespec_translate ($) {

IkiWiki/Plugin/tag.pm

@@ -72,7 +72,7 @@ sub gentag ($) {
 		my $tagfile = newpagefile(tagpage($tag), $config{default_pageext});
 		$tagfile=~s/^\///;
 
-		return if (! add_autofile($tagfile));
+		return if (! add_autofile($tagfile, "tag"));
 
 		debug(sprintf(gettext("creating tag page %s"), $tag));
 

IkiWiki/Render.pm

@@ -637,12 +637,14 @@ sub refresh () {
 	my ($changed, $internal_changed)=find_changed($files);
 	run_hooks(needsbuild => sub { shift->($changed) });
 	my $oldlink_targets=calculate_old_links($changed, $del);
+	%del_hash = map { $_ => 1 } @{$del};
 
 	foreach my $file (@$changed) {
 		scan($file);
 	}
 
-	while (my $autofile = shift (@autofiles)) {
+	while (my $autofile = shift @{[keys %autofiles]}) {
+		my $plugin=$autofiles{$autofile};
 		my $page=pagename($autofile);
 		if ($pages->{$page}) {
 			debug(sprintf(gettext("%s has multiple possible source pages"), $page));
@@ -654,6 +656,7 @@ sub refresh () {
 		push @{$changed}, $autofile if find_changed([$autofile]);
 
 		scan($autofile);
+		delete $autofiles{$autofile};
 	}
 
 	calculate_links();