Correct the syntax for standard_gtest_merge.py

It was changed in crrev.com/c/3313767. But it reports syntax error under
py2 and as a result the "Result Details" is missing on the android
builders.

Bug: 1262303, 1245494, 1255217
Change-Id: I85f2ec6d090c30cb717274644fa3ce703866ce0c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3330796
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/main@{#950836}

build/android/pylib/results/presentation/standard_gtest_merge.py

@@ -21,8 +21,11 @@ def merge_shard_results(summary_json, jsons_to_merge):
   try:
     with open(summary_json) as f:
       summary = json.load(f)
-  except (IOError, ValueError) as e:
-    raise Exception('Summary json cannot be loaded.') from e
+  except (IOError, ValueError):
+    # TODO(crbug.com/1245494):Re-enable this check after the recipe module
+    # chromium_swarming can run it with py3
+    # pylint: disable=raise-missing-from
+    raise Exception('Summary json cannot be loaded.')
 
   # Merge all JSON files together. Keep track of missing shards.
   merged = {