Revert "Make the mton payload optional when staging artifacts."

This reverts commit 97b6489c878303aa294bc888036235fc7ee9148e

Change-Id: I55548cc7d5d96177c17a152fe4dd4c142c92d8c3
Reviewed-on: https://gerrit.chromium.org/gerrit/19980
Commit-Ready: Scott Zawalski <scottz@chromium.org>
Reviewed-by: Scott Zawalski <scottz@chromium.org>
Tested-by: Scott Zawalski <scottz@chromium.org>
diff --git a/devserver_util.py b/devserver_util.py
index eb498f4..fa92a97 100644
--- a/devserver_util.py
+++ b/devserver_util.py
@@ -50,7 +50,7 @@
       else:
         mton_payload_url = payload
 
-  if not full_payload_url or not nton_payload_url:
+  if not full_payload_url or not nton_payload_url or not mton_payload_url:
     raise DevServerUtilError(
         'Payloads are missing or have unexpected name formats.', payload_list)
 
@@ -74,17 +74,16 @@
   full_payload = os.path.join(build_dir, downloadable_artifact.ROOT_UPDATE)
   nton_payload = os.path.join(build_dir, AU_BASE, build + NTON_DIR_SUFFIX,
                               downloadable_artifact.ROOT_UPDATE)
+  mton_payload = os.path.join(build_dir, AU_BASE, build + MTON_DIR_SUFFIX,
+                              downloadable_artifact.ROOT_UPDATE)
 
   artifacts = []
   artifacts.append(downloadable_artifact.DownloadableArtifact(full_url,
       main_staging_dir, full_payload, synchronous=True))
   artifacts.append(downloadable_artifact.AUTestPayload(nton_url,
       main_staging_dir, nton_payload))
-  if mton_url:
-    mton_payload = os.path.join(build_dir, AU_BASE, build + MTON_DIR_SUFFIX,
-                                downloadable_artifact.ROOT_UPDATE)
-    artifacts.append(downloadable_artifact.AUTestPayload(
-        mton_url, main_staging_dir, mton_payload))
+  artifacts.append(downloadable_artifact.AUTestPayload(mton_url,
+      main_staging_dir, mton_payload))
 
   # Next we gather the miscellaneous payloads.
   stateful_url = archive_url + '/' + downloadable_artifact.STATEFUL_UPDATE