bugfix: improve transclusion matching

bug reported by moebiusband73

impermanence.pl

@@ -77,7 +77,7 @@ sub remove_transclusion {
         # check if a file is contained by a directory
         foreach my $file (@files) {
             my($filename, $dirs, $suffix) = fileparse($file);
-            if( $dirs =~ m/^$dir/ ) {
+            if( $dirs =~ m|^$dir/| ) {
                 saywarning("WARNING: $dir contains $file");
                 $file = "";
             }