commit d3878c87910e29601c598204028eddef0e59c8ca
Author: Tom Hughes <tom@compton.nu>
Date:   Fri Jul 5 19:19:25 2013 +0100

    Workaround precision issues

diff --git a/test/image.test.js b/test/image.test.js
index 7b6922e..3883585 100644
--- a/test/image.test.js
+++ b/test/image.test.js
@@ -203,7 +203,7 @@ describe('mapnik.Image ', function() {
         assert.equal(pixel3.r, 0);
         assert.equal(pixel3.g, 128);
         assert.equal(pixel3.b, 0);
-        assert.equal(pixel3.a, 255);
+        assert(pixel3.a == 254 || pixel3.a == 255);
     });
 
     it('should support setting an individual pixel', function() {