interactive: correctly load non-ascii logs

Some packages write utf-8 in logs, and may write
build logs in other charset. Now we can load
such logs more or less correctly.

port_stats/interactive.py

@@ -188,7 +188,7 @@ def fti(num, to=print):
 def logs(num, idx=-1, to=pager):
     log_file = m_logs.task_event_logs(get_task(num, TASKS))[idx]
     with open(log_file, 'r') as f:
-        log = f.read()
+        log = f.read().decode('utf-8', errors='replace')
     to(log_file + ':\n\n' + log)