Making script backward compatible with python2

[aruniiird]

Signed-off-by: Arun Kumar Mohan amohan@redhat.com

Description of your changes:
As exec is an internal builtin function for python2 there were some errors thrown while running the script with python2.
Changed the variable name to execErr.

Which issue is resolved by this Pull Request:
Resolves #

Checklist:

• Commit Message Formatting: Commit titles and messages follow guidelines in the developer guide.
• Skip Tests for Docs: Add the flag for skipping the build if this is only a documentation change. See here for the flag.
• Skip Unrelated Tests: Add a flag to run tests for a specific storage provider. See test options.
• Reviewed the developer guide on Submitting a Pull Request
• Documentation has been updated, if necessary.
• Unit tests have been added, if necessary.
• Integration tests have been added, if necessary.
• Pending release notes updated with breaking and/or notable changes, if necessary.
• Upgrade from previous release is tested and upgrade user guide is updated, if necessary.
• Code generation (make codegen) has been run to update object specifications, if necessary.

[leseb]

Please change the commit title and add a commit message. Otherwise LGTM

[travisn]

Looks like the external cluster test script is failing:

+ timeout 10 sh -c 'until kubectl -n rook-ceph exec rook-ceph-tools-78cdfd976c-g84kv -- python3 /etc/ceph/create-external-cluster-resources.py --rbd-data-pool-name replicapool; do echo '\''waiting for script to succeed'\'' && sleep 1; done'
</html>Execution Failed: unable to connect to endpoint: 172.17.0.8:9283
Traceback (most recent call last):
  File "/etc/ceph/create-external-cluster-resources.py", line 907, in <module>
    raise err
  File "/etc/ceph/create-external-cluster-resources.py", line 904, in <module>
    rjObj.main()
  File "/etc/ceph/create-external-cluster-resources.py", line 885, in main
    generated_output = self.gen_json_out()
  File "/etc/ceph/create-external-cluster-resources.py", line 691, in gen_json_out
    self._gen_output_map()
  File "/etc/ceph/create-external-cluster-resources.py", line 672, in _gen_output_map
    self.out_map['MONITORING_ENDPOINT_PORT'] = self.get_active_and_standby_mgrs()
  File "/etc/ceph/create-external-cluster-resources.py", line 422, in get_active_and_standby_mgrs
    self.endpoint_dial(monitoring_endpoint)
  File "/etc/ceph/create-external-cluster-resources.py", line 267, in endpoint_dial
    "unable to connect to endpoint: {}".format(endpoint_str))

[aruniiird]

/retest

[aruniiird]

Can we do a retest? I highly doubt this failure has anything to do with current change...

[travisn]

Rerunning the CI did not repro the error, and the error was also seen in a separate run from this PR, so it is unrelated.