Recognise and ignore Enhances: lines

Patch from Ian Campbell.

It seems that "apt-cache depends" recently (as of 0.7.22) started
including Enhances lines in its output. Leading to:

 Generating dependency tree with apt-cache depends...
        UNEXPECTED: Line `  Enhances: kvm
        ' while parsing end of deptree from 'kvm-source'
        [etc....]

Ignore these lines.

debian/changelog

@@ -22,6 +22,7 @@ debian-cd (3.1.3) UNRELEASED; urgency=low
   * Add support for "variants". A variant allows to include/exclude additional
     packages or D-I components relative to a regular image.
   * Add variant to create i386/amd64 images that support installing Xen guests.
+  * Recognise and ignore Enhances: lines.
 
  -- Frans Pop <fjp@debian.org>  Tue, 04 Aug 2009 22:32:08 +0200
 

tools/sort_deps

@@ -308,7 +308,7 @@ sub read_depends {
 	my $i = shift;     # Ref
 	my $lines = shift; # Ref
 	my $pkg = shift;   # string
-	my $types = "(?:Pre)?Depends|Suggests|Recommends|Replaces|Conflicts|Breaks";
+	my $types = "(?:Pre)?Depends|Suggests|Recommends|Replaces|Conflicts|Breaks|Enhances";
 	my (@dep, @rec, @sug);
 	my ($type, $or, $elt);
 
@@ -317,7 +317,8 @@ sub read_depends {
 		# Get rid of replaces and conflicts ...
 		if (($type eq "Replaces") or
 			($type eq "Conflicts") or
-			($type eq "Breaks")) {
+			($type eq "Breaks") or
+			($type eq "Enhances")) {
 			$$i++;
 			while ($lines->[$$i] =~ m/^\s{4}/) {
 				$$i++;