python: Update the gem5 lib downloader 'is_zipped' checker

Previously, gem5 resources' resources.json file set the 'is_zipped'
field to a string, either "True" or "False". As JSON supports booleans,
this was updated in an upcoming patch to use boolean values instead:
https://gem5-review.googlesource.com/c/public/gem5-resources/+/51168.

This patch updates the gem5 library downloader to use the new true/false
values but remains backwards compataible with the old string-based way
of declaring the value of this field.

Change-Id: I804ce66e8ca1989955b09041b7d1c894de74dac0
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/51329
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/python/gem5/resources/downloader.py

@@ -251,7 +251,24 @@ def get_resource(
                 )
 
         download_dest = to_path
-        run_unzip = unzip and resource_json["is_zipped"].lower() == "true"
+
+        # This if-statement is remain backwards compatable with the older,
+        # string-based way of doing things. It can be refactored away over
+        # time:
+        # https://gem5-review.googlesource.com/c/public/gem5-resources/+/51168
+        if isinstance(resource_json["is_zipped"], str):
+            run_unzip = unzip and resource_json["is_zipped"].lower() == "true"
+        elif isinstance(resource_json["is_zipped"], bool):
+            run_unzip = unzip and resource_json["is_zipped"]
+        else:
+            raise Exception(
+                "The resource.json entry for '{}' has a value for the "
+                "'is_zipped' field which is neither a string or a boolean."
+                .format(
+                    resource_name
+                )
+            )
+
         if run_unzip:
             download_dest += ".gz"