It turns out that while the terminal accepts unicode characters, buildbot's stdout and stderr does not. We should handle this case in the MeteredStream object.
<rdar://problem/46788706>
Created attachment 357473 [details] Patch
Comment on attachment 357473 [details] Patch Clearing flags on attachment: 357473 Committed r239303: <https://trac.webkit.org/changeset/239303>
All reviewed patches have been landed. Closing bug.