Ensure that download command exits properly (resolves #1714)

spacy/cli/download.py

@@ -31,7 +31,10 @@ def download(cmd, model, direct=False):
         version = get_version(model_name, compatibility)
         dl = download_model('{m}-{v}/{m}-{v}.tar.gz'.format(m=model_name,
                                                             v=version))
-        if dl == 0:
+        if dl != 0:
+            # if download subprocess doesn't return 0, exit with the respective
+            # exit code before doing anything else
+            sys.exit(dl)
         try:
             # Get package path here because link uses
             # pip.get_installed_distributions() to check if model is a