gsutil: Decode output from subprocess.

Bug: 1007872, 1009819
Change-Id: Icb24badc0429012dc66912d7d35e03a456512787
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1894354
Reviewed-by: Anthony Polito <apolito@google.com>
Commit-Queue: Edward Lesmes <ehmaldonado@chromium.org>
diff --git a/gsutil.py b/gsutil.py
index 64e4b5c..8d5de5d 100755
--- a/gsutil.py
+++ b/gsutil.py
@@ -140,7 +140,8 @@
     # This script requires Windows Python, so invoke with depot_tools'
     # Python.
     def winpath(path):
-      return subprocess.check_output(['cygpath', '-w', path]).strip()
+      stdout = subprocess.check_output(['cygpath', '-w', path])
+      return stdout.strip().decode('utf-8', 'replace')
     cmd = ['python.bat', winpath(__file__)]
     cmd.extend(args)
     sys.exit(subprocess.call(cmd))