[CircleCI] use matching names for storing and restoring ATen cache

8a80728 (Sun Apr 22 08:54:09 2018
-0700) replaced ATen submodule with PyTorch, updating the test script
instructions.  On build-1404 instances, it changed the compilation cache
key prefix from v1-aten to v1-pytorch when restoring, but did not change
the prefix for storing the compiled files.  As a result, ATen is being
recompiled on every test run unnecessarily.  Use v1-aten as key prefix
in both storing and restoring the compilation cache.  -aten is chosen
over -pytorch for consistency with build-1604.

Author: ftynse

.circleci/config.yml

@@ -26,7 +26,7 @@ jobs:
 
       - restore_cache:
           keys:
-            - v1-pytorch-{{ checksum ".git/modules/third-party/pytorch/HEAD" }}-{{ checksum "build.sh" }}-{{ checksum ".circleci/config.yml" }}-{{ arch }}-1404
+            - v1-aten-{{ checksum ".git/modules/third-party/pytorch/HEAD" }}-{{ checksum "build.sh" }}-{{ checksum ".circleci/config.yml" }}-{{ arch }}-1404
 
       - restore_cache:
           keys: