modules.pkg int tests: skip refresh_db upon error

[jfindlay]

What does this PR do?

Skip the test when there is an error:

Error Message

'str' object has no attribute 'items'

Stacktrace

Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/salttesting/helpers.py", line 547, in wrapper
    return func(cls)
  File "/usr/local/lib/python2.7/dist-packages/salttesting/helpers.py", line 68, in wrap
    return caller(cls)
  File "/testing/tests/integration/modules/pkg.py", line 197, in test_refresh_db
    for source, state in ret.items():
AttributeError: 'str' object has no attribute 'items'

Standard Output

Standard Error

What issues does this PR fix or reference?

Tests written?

Yes