Fix issues with backend native

Author: Eric Arellano

src/python/pants/backend/native/targets/native_artifact.py

@@ -29,4 +29,5 @@ def as_shared_lib(self, platform):
 
   def _compute_fingerprint(self):
     # FIXME: can we just use the __hash__ method here somehow?
-    return sha1(self.lib_name).hexdigest() if PY3 else sha1(self.lib_name).hexdigest().decode('utf-8')
+    hasher = sha1(self.lib_name.encode('utf-8'))
+    return hasher.hexdigest() if PY3 else hasher.hexdigest().decode('utf-8')

tests/python/pants_test/backend/native/subsystems/test_native_toolchain.py

@@ -134,7 +134,7 @@ def _invoke_capturing_output(self, cmd, env=None):
       env = os.environ.copy()
     try:
       with environment_as(**env):
-        return subprocess.check_output(cmd, stderr=subprocess.STDOUT)
+        return subprocess.check_output(cmd, stderr=subprocess.STDOUT).decode('utf-8')
     except subprocess.CalledProcessError as e:
       raise Exception(
         "Command failed while invoking the native toolchain "