https://bugs.gentoo.org/666948

and required for rust-1.33 patch

--- a/python/mozbuild/mozbuild/controller/building.py
+++ b/python/mozbuild/mozbuild/controller/building.py
@@ -571,7 +571,7 @@ class TerminalLoggingHandler(logging.Handler):
             if self.footer:
                 self.footer.clear()
 
-            self.fh.write(msg)
+            self.fh.write(msg.encode("utf-8"))
             self.fh.write('\n')
 
             if self.footer: