Defining system default encoding in log file header comment.

IPython/Magic.py

@@ -1164,7 +1164,7 b' Currently the magic system has the following functions:\\n"""'
         if logfname:
             logfname = os.path.expanduser(logfname)
         rc.opts.logfile = logfname
-        loghead = self.shell.loghead_tpl % (rc.opts,rc.args)
+        loghead = self.shell.loghead_tpl % (sys.stdin.encoding, rc.opts, rc.args)
         try:
             started  = logger.logstart(logfname,loghead,logmode,
                                        log_output,timestamp,log_raw_input)

IPython/iplib.py

@@ -670,7 +670,7 b' class InteractiveShell(object,Magic):'
         # logstart method.
         self.loghead_tpl = \
 """#log# Automatic Logger file. *** THIS MUST BE THE FIRST LINE ***
-#log# DO NOT CHANGE THIS LINE OR THE TWO BELOW
+#log# DO NOT CHANGE THIS LINE OR THE TWO BELOW -* coding: %s *-
 #log# opts = %s
 #log# args = %s
 #log# It is safe to make manual edits below here.