gitweb: Show "no difference" message for empty diff

Currently, gitweb shows only header and footer, if no differences are
found. This patch adds a "No differences found" message for the html
output.
Signed-off-by: NMartin Koegler <mkoegler@auto.tuwien.ac.at>
Signed-off-by: NJakub Narebski <jnareb@gmail.com>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

gitweb/gitweb.css

@@ -387,6 +387,10 @@ div.diff.incomplete {
 	color: #cccccc;
 }
 
+div.diff.nodifferences {
+	font-weight: bold;
+	color: #600000;
+}
 
 div.index_include {
 	border: solid #d9d8d1;

gitweb/gitweb.perl

@@ -2398,6 +2398,7 @@ sub git_patchset_body {
 	my ($fd, $difftree, $hash, $hash_parent) = @_;
 
 	my $patch_idx = 0;
+	my $patch_number = 0;
 	my $patch_line;
 	my $diffinfo;
 	my (%from, %to);
@@ -2419,6 +2420,7 @@ sub git_patchset_body {
 		# git diff header
 		#assert($patch_line =~ m/^diff /) if DEBUG;
 		#assert($patch_line !~ m!$/$!) if DEBUG; # is chomp-ed
+		$patch_number++;
 		push @diff_header, $patch_line;
 
 		# extended diff header
@@ -2581,6 +2583,7 @@ sub git_patchset_body {
 	} continue {
 		print "</div>\n"; # class="patch"
 	}
+	print "<div class=\"diff nodifferences\">No differences found</div>\n" if (!$patch_number);
 
 	print "</div>\n"; # class="patchset"
 }