patch for git's diff-highlight to show utf8 strings properly. originally from https://gist.github.com/kaosf/d361cd5169fb36297d9c

diff-highlight.utf8.patch

--- diff-highlight.org	2014-06-02 11:39:23.000000000 +0900
+++ diff-highlight	2014-06-02 11:50:13.000000000 +0900
@@ -3,6 +3,8 @@
 use warnings FATAL => 'all';
 use strict;
 
+use Encode qw(decode_utf8 encode_utf8);
+
 # Highlight by reversing foreground and background. You could do
 # other things like bold or underline if you prefer.
 my $HIGHLIGHT   = "\x1b[7m";
@@ -20,10 +22,10 @@
 		$in_hunk = /^$COLOR*\@/;
 	}
 	elsif (/^$COLOR*-/) {
-		push @removed, $_;
+		push @removed, decode_utf8($_);
 	}
 	elsif (/^$COLOR*\+/) {
-		push @added, $_;
+		push @added, decode_utf8($_);
 	}
 	else {
 		show_hunk(\@removed, \@added);
@@ -58,7 +60,7 @@
 
 	# If one side is empty, then there is nothing to compare or highlight.
 	if (!@$a || !@$b) {
-		print @$a, @$b;
+		print encode_utf8($_) for @$a, @$b;
 		return;
 	}
 
@@ -67,17 +69,17 @@
 	# stupid, and only handle multi-line hunks that remove and add the same
 	# number of lines.
 	if (@$a != @$b) {
-		print @$a, @$b;
+		print encode_utf8($_) for @$a, @$b;
 		return;
 	}
 
 	my @queue;
 	for (my $i = 0; $i < @$a; $i++) {
 		my ($rm, $add) = highlight_pair($a->[$i], $b->[$i]);
-		print $rm;
+		print encode_utf8($rm);
 		push @queue, $add;
 	}
-	print @queue;
+	print encode_utf8($_) for @queue;
 }
 
 sub highlight_pair {

HOW

$ wget https://raw.githubusercontent.com/git/git/34d9819e0a387be6d49cffe67458036450d6d0d5/contrib/diff-highlight/diff-highlight
$ wget https://gist.githubusercontent.com/a2ikm/2dbfb89114dfa5c543ed/raw/e2d8d550ef601c9310712f4187b803658427dd42/diff-highlight.utf8.patch
$ patch -u diff-highlight < diff-highlight.utf8.patch
$ chmod +x diff-highlight