[autotest] cros_repair: test a portable python module

cPickle only exists in Python 2, so switch to json which exists in both.

BUG=chromium:990593
TEST=CQ passes

Change-Id: Icf207f5827ef01e4138371830c927247de1ecf1c
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/1925415
Reviewed-by: Greg Edelston <gredelston@google.com>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
(cherry picked from commit 6d7fb2a58768b33f239549fb709bfcb487bc5e53)
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/1951904
Reviewed-by: Keith Haddow <haddowk@chromium.org>
Commit-Queue: Keith Haddow <haddowk@chromium.org>
Tested-by: Keith Haddow <haddowk@chromium.org>
diff --git a/server/hosts/cros_repair.py b/server/hosts/cros_repair.py
index fa709a0..85802f9 100644
--- a/server/hosts/cros_repair.py
+++ b/server/hosts/cros_repair.py
@@ -251,7 +251,7 @@
 
     def verify(self, host):
         # pylint: disable=missing-docstring
-        result = host.run('python -c "import cPickle"',
+        result = host.run('python -c "import json"',
                           ignore_status=True)
         if result.exit_status != 0:
             message = 'The python interpreter is broken'