Only log spec output on failures

build/tasks/spec-task.coffee

@@ -39,7 +39,8 @@ module.exports = (grunt) ->
       grunt.verbose.writeln "Launching #{path.basename(packagePath)} specs."
       spawn options, (error, results, code) ->
         if process.platform is 'win32'
-          process.stderr.write(fs.readFileSync(path.join(packagePath, 'ci.log')))
+          if error
+            process.stderr.write(fs.readFileSync(path.join(packagePath, 'ci.log')))
           fs.unlinkSync(path.join(packagePath, 'ci.log'))
 
         failedPackages.push path.basename(packagePath) if error
@@ -77,7 +78,7 @@ module.exports = (grunt) ->
 
     spawn options, (error, results, code) ->
       if process.platform is 'win32'
-        process.stderr.write(fs.readFileSync('ci.log'))
+        process.stderr.write(fs.readFileSync('ci.log')) if error
         fs.unlinkSync('ci.log')
       else
         # TODO: Restore concurrency on Windows