git hyper_blame might use a subprocess' stdin for its stdout,
which is opened to accept byte input.
The text must be encoded before printing to stdout to avoid
unicode errors.

Bug: 1028709
Change-Id: If2a270a7f3f69a818d367616f6732245de364db9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1937500Reviewed-by: Andy Perelson <ajp@chromium.org>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>