[push-package] Update error msg

Error message should make it clear that push-apckages will not work with
"package_name" for now.

Can be reverted when BLD-338 is resolved

Change-Id: Ifac356eafc905ddc956b57984347b251c73ea683
diff --git a/devshell/push-package b/devshell/push-package
index 4e2a715..76349b8 100755
--- a/devshell/push-package
+++ b/devshell/push-package
@@ -46,7 +46,8 @@
           continue 2
         fi
       done
-      echo >&2 "Package $pkg will not be pushed. It is not part of the current build, is not a package, or has 'deprecated_system_image=true'."
+      # TODO(BLD-338): Remove "package_name" from error message
+      echo >&2 "Package $pkg will not be pushed. It is not part of the current build, is not a package, overrides 'package_name=\"...\"' or has 'deprecated_system_image=true'."
       exit 1
     done
   fi