lib/logger.rb: use %N

* lib/logger.rb (format_datetime): use "%6N" to show microsecond.
  [Fix GH-704]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47271 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Mon Aug 25 12:56:54 2014  Ivan Korunkov  <ivankorunkov@ya.ru>
+
+	* lib/logger.rb (format_datetime): use "%6N" to show microsecond.
+	  [Fix GH-704]
+
 Mon Aug 25 11:02:07 2014  Eric Wong  <e@80x24.org>
 
 	* vm_core.h (rb_iseq_location_t): change first_lineno type to VALUE

lib/logger.rb

@@ -511,7 +511,7 @@ private
 
     def format_datetime(time)
       if @datetime_format.nil?
-        time.strftime("%Y-%m-%dT%H:%M:%S.") << "%06d " % time.usec
+        time.strftime("%Y-%m-%dT%H:%M:%S.%6N ")
       else
         time.strftime(@datetime_format)
       end