Hello
In our repository i found a text file with some very strange encoding.
I fixed up the file and committed for review with "arc diff".
Now the tool warns me that it is not a valid utf8 file, like this:
```
Invalid Content Encoding (Non-UTF8)
This diff includes a file which is not valid UTF-8 (it has invalid byte
sequences). You can either stop this workflow and fix it, or continue. If you
continue, this file will be marked as binary.
```
so, according to "UTF-8 and Character Encoding" i ran the utf8.php script on the file,
but it reports "OK":
```
$ libphutil/scripts/utils/utf8.php ~/repo/doc/utf8.txt
OKAY /Users/ml/repo/doc/utf8.txt
```
I suspect that the check is confused by the fact that the old version of the file (and the resulting diff)
will contain non-valid utf8 characters.
The problem now is that my file is marked as binary in order to send the diff to phabricator, and
it is not easy for reviewer to see my changes.